Method for channel estimation and pilot reception for remote radio head (rrh) deployments and multi-antenna downlink mimo

ABSTRACT

A method and apparatus for determining pilot information is disclosed. A wireless/transmit receive unit (WTRU) receives a plurality of high speed shared control channel (HS-SCCH) resources including radio resource control (RRC) configuration information for high speed downlink packet access (HSDPA), wherein the RRC configuration information includes dedicated pilot information associated with each received HS-SCCH resource. The WTRU detects a high speed downlink shared channel (HS-DSCH) radio network transmission identifier (H-RNTI) associated with the WTRU in one of the plurality of HS-SCCH resources. The WTRU determines pilot information, based on the dedicated pilot information and the one of the plurality of HS-SCCH resources, for a high speed physically downlink shared channel (HS-PDSCH) associated with the one of the plurality of HS-SCCH resources.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/572,040, filed Aug. 10, 2012, which claims the benefit of U.S.Provisional Application No. 61/522,842 filed Aug. 12, 2011, U.S.Provisional Application No. 61/541,714 filed Sep. 30, 2011, U.S.Provisional Application No. 61/555,840 filed Nov. 4, 2011, and U.S.Provisional Application No. 61/591,577 filed Jan. 27, 2012, the contentsof which are hereby incorporated by reference herein.

BACKGROUND

In response to increasing demand in terms of higher peak data rate andbetter user experience from end users, third generation partnershipproject (3GPP) wireless communication systems involving wideband codedivision multiple access (WCDMA) technologies have been evolving,whereby many new features have been proposed and specified. For example,a new feature that allows the simultaneous use of two high speeddownlink (DL) packet access (HSDPA) downlink carriers has beenintroduced. This new feature essentially improves the bandwidth usageand user peak downlink rate via frequency aggregation and resourcepooling, and was extended to include a multiple-input multiple-output(MIMO) function. Later, four (4) carrier HSDPA (4C-HSDPA) was introducedwhich allows up to four (4) carriers to operate simultaneously toincrease the downlink throughput.

As efforts to improve user experience at cell edge continue, coordinatedHSDPA transmission involving multiple cells operates in the samefrequency to deploy and support multipoint (MP) downlink transmission.Remote radio head (RRH) is an important technology that may simplify thedeployment of the multipoint downlink transmission.

SUMMARY

A method and apparatus for determining pilot information is disclosed. Awireless/transmit receive unit (WTRU) receives a plurality of high speedshared control channel (HS-SCCH) resources including radio resourcecontrol (RRC) configuration information for high speed downlink packetaccess (HSDPA), wherein the RRC configuration information includesdedicated pilot information associated with each received HS-SCCHresource. The WTRU detects a high speed downlink shared channel(HS-DSCH) radio network transmission identifier (H-RNTI) associated withthe WTRU in one of the plurality of HS-SCCH resources. The WTRUdetermines pilot information, based on the dedicated pilot informationand the one of the plurality of HS-SCCH resources, for a high speedphysically downlink shared channel (HS-PDSCH) associated with the one ofthe plurality of HS-SCCH resources.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1A is a system diagram of an example communications system in whichone or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram of an example wireless transmit/receive unit(WTRU) that may be used within the communications system illustrated inFIG. 1A;

FIG. 1C is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 1A;

FIG. 2 is an example of a conventional homogeneous network deployment;

FIG. 3 is an example of a network deployment with RRH, wherein the RRHacts as an independent cell;

FIG. 4 is an example of utilizing common scrambling code (CSC) amongRRHs in UMTS;

FIG. 5 is an example of joint MP-HSDPA transmission mode;

FIG. 6 is an example of multiflow aggregation to the same WTRUs;

FIG. 7 is an example of multiflow aggregation for single celltransmission to a single WTRU;

FIG. 8 is an example of 4 branch DL-MIMO operating at individual RRH;

FIG. 9 is an example of 4 branch DL-MIMO when RRHs are used as simpleantenna extensions;

FIG. 10 is an example modulation pattern and channelization codeassignment for four common pilot channels;

FIG. 11 is a first example modulation pattern and channelization codeassignment for six common pilot channels;

FIG. 12 is a second example modulation pattern and channelization codeassignment for six common pilot channels;

FIG. 13 is an example of pilot indexing with rank indication;

FIG. 14 is an example of time multiplexing WTRU-specific pilot with ahigh speed-physical downlink shared channel (HS-PDSCH);

FIG. 15 is an example of time multiplexing WTRU-specific pilot withHS-PDSCH on one channelization code;

FIG. 16 is an example of time multiplexing WTRU-specific pilot withHS-PDSCH on one channelization code and discontinuously transmitting thepilot portion of HS PDSCHs on all other channelization codes;

FIG. 17 is an example of time multiplexing WTRU-specific pilot withHS-PDSCH on all assigned channelization codes (up to 15);

FIG. 18 is an example of pilot resource allocation for demodulation ofHS-SCCH and HS-PDSCH;

FIG. 19 shows a time multiplexing WTRU-specific pilot with HS-PDSCH onone channelization code;

FIG. 20 is an example of the coding chain for HS-SCCH type 4;

FIG. 21 is an example of a coding chain for HS-SCCH for a non-codebookbased MIMO scheme with 4 transport blocks;

FIG. 22 is an example of a coding chain for HS-SCCH for a codebook basedMIMO scheme with 4 transport blocks; and

FIG. 23 is an example of a method for determining pilot information foreach data stream.

DETAILED DESCRIPTION

FIG. 1A is a diagram of an example communications system 100 in whichone or more disclosed embodiments may be implemented. The communicationssystem 100 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications system 100may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a radioaccess network (RAN) 104, a core network 106, a public switchedtelephone network (PSTN) 108, the Internet 110, and other networks 112,though it will be appreciated that the disclosed embodiments contemplateany number of WTRUs, base stations, networks, and/or network elements.Each of the WTRUs 102 a, 102 b, 102 c, 102 d may be any type of deviceconfigured to operate and/or communicate in a wireless environment. Byway of example, the WTRUs 102 a, 102 b, 102 c, 102 d may be configuredto transmit and/or receive wireless signals and may include userequipment (UE), a mobile station, a fixed or mobile subscriber unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,consumer electronics, and the like.

The communications system 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the core network 106, the Internet 110,and/or the networks 112. By way of example, the base stations 114 a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a HomeNode B, a Home eNode B, a site controller, an access point (AP), awireless router, and the like. While the base stations 114 a, 114 b areeach depicted as a single element, it will be appreciated that the basestations 114 a, 114 b may include any number of interconnected basestations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114 a may be divided intothree sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Theair interface 116 may be established using any suitable radio accesstechnology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed DownlinkPacket Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1×, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 114 band the WTRUs 102 c, 102 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114 b and the WTRUs 102 c, 102 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1A,the base station 114 b may have a direct connection to the Internet 110.Thus, the base station 114 b may not be required to access the Internet110 via the core network 106.

The RAN 104 may be in communication with the core network 106, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. For example, the core network 106may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the core network 106 may be in direct orindirect communication with other RANs that employ the same RAT as theRAN 104 or a different RAT. For example, in addition to being connectedto the RAN 104, which may be utilizing an E-UTRA radio technology, thecore network 106 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 106 may also serve as a gateway for the WTRUs 102 a,102 b, 102 c, 102 d to access the PSTN 108, the Internet 110, and/orother networks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired or wireless communications networks ownedand/or operated by other service providers. For example, the networks112 may include another core network connected to one or more RANs,which may employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, i.e., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram of an example WTRU 102. As shown in FIG. 1B,the WTRU 102 may include a processor 118, a transceiver 120, atransmit/receive element 122, a speaker/microphone 124, a keypad 126, adisplay/touchpad 128, non-removable memory 130, removable memory 132, apower source 134, a global positioning system (GPS) chipset 136, andother peripherals 138. It will be appreciated that the WTRU 102 mayinclude any sub-combination of the foregoing elements while remainingconsistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In another embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and receive both RF and light signals. It will be appreciatedthat the transmit/receive element 122 may be configured to transmitand/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 1C is a system diagram of the RAN 104 and the core network 106according to an embodiment. As noted above, the RAN 104 may employ aUTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102 cover the air interface 116. The RAN 104 may also be in communicationwith the core network 106. As shown in FIG. 1C, the RAN 104 may includeNode-Bs 140 a, 140 b, 140 c, which may each include one or moretransceivers for communicating with the WTRUs 102 a, 102 b, 102 c overthe air interface 116. The Node-Bs 140 a, 140 b, 140 c may each beassociated with a particular cell (not shown) within the RAN 104. TheRAN 104 may also include RNCs 142 a, 142 b. It will be appreciated thatthe RAN 104 may include any number of Node-Bs and RNCs while remainingconsistent with an embodiment.

As shown in FIG. 1C, the Node-Bs 140 a, 140 b may be in communicationwith the RNC 142 a. Additionally, the Node-B 140 c may be incommunication with the RNC 142 b. The Node-Bs 140 a, 140 b, 140 c maycommunicate with the respective RNCs 142 a, 142 b via an Iub interface.The RNCs 142 a, 142 b may be in communication with one another via anIur interface. Each of the RNCs 142 a, 142 b may be configured tocontrol the respective Node-Bs 140 a, 140 b, 140 c to which it isconnected. In addition, each of the RNCs 142 a, 142 b may be configuredto carry out or support other functionality, such as outer loop powercontrol, load control, admission control, packet scheduling, handovercontrol, macrodiversity, security functions, data encryption, and thelike.

The core network 106 shown in FIG. 1C may include a media gateway (MGW)144, a mobile switching center (MSC) 146, a serving GPRS support node(SGSN) 148, and/or a gateway GPRS support node (GGSN) 150. While each ofthe foregoing elements are depicted as part of the core network 106, itwill be appreciated that any one of these elements may be owned and/oroperated by an entity other than the core network operator.

The RNC 142 a in the RAN 104 may be connected to the MSC 146 in the corenetwork 106 via an IuCS interface. The MSC 146 may be connected to theMGW 144. The MSC 146 and the MGW 144 may provide the WTRUs 102 a, 102 b,102 c with access to circuit-switched networks, such as the PSTN 108, tofacilitate communications between the WTRUs 102 a, 102 b, 102 c andtraditional land-line communications devices.

The RNC 142 a in the RAN 104 may also be connected to the SGSN 148 inthe core network 106 via an IuPS interface. The SGSN 148 may beconnected to the GGSN 150. The SGSN 148 and the GGSN 150 may provide theWTRUs 102 a, 102 b, 102 c with access to packet-switched networks, suchas the Internet 110, to facilitate communications between and the WTRUs102 a, 102 b, 102 c and IP-enabled devices.

As noted above, the core network 106 may also be connected to thenetworks 112, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

Remote Radio Head (RRH) is an important technology that may simplify thedeployment of systems supporting multiple HSDPA transmission, as itallows a plurality of Node-Bs in coordination to be collocated whiledistributing the transmitted signal to the radio frequency (RF) units indifferent locations. RRH configurations may also be used for long termevolution (LTE) coordinated multiple point (CoMP) transmission, such asin a homogeneous network with intra-site Comp, a homogeneous networkwith high transmit (Tx) power RRHs, a heterogeneous network with lowpower RRHs within the macro-cell coverage with different cell identities(IDs), and a heterogeneous network with low power RRHs within themacro-cell coverage with same cell IDs.

A heterogeneous network with low power RRHs within the macro-cellcoverage with same cell IDs may be of particular interest, where acommon cell-ID is shared among the transmission points, (macro pointsand pico points), within the coverage area of a macro point. Whilemaintaining similar cell splitting gain as independent multiple cells,this deployment configuration may offer the advantages of improvedcoverage of the sync and control channels as they may be commonlytransmitted from the multiple points. In addition, the WTRU mobility maybe greatly improved in the heterogeneous network, and the number ofhandovers may be considerably reduced, especially if aggressive use ofrange extension is employed. Furthermore, as a result of the improvedWTRU mobility, the network may dynamically and seamlessly allocate datatraffic to the WTRU among various macro and pico cells, leading toadditional resource pooling gain for scheduling optimization.

In another aspect, a more realistic deployment scenario relevant to theabove cell configuration may consider the RRHs as, or actually consistof, multiple antennas in one base station. While current WCDMA downlinkMIMO operations are specified for up to two (2) spatial multiplexingstreams in an LTE system, spatial multiplexing on the order of eight (8)may be possible. In order to take advantage of MIMO operations, multipleantennas may be used at both the transmitter and the receiver. Sincepractical deployment may share some of the antennas for both LTE andWCDMA systems, many sites for WCDMA may have access to two or moreantennas.

In one example, four (4) MIMO streams may be supported for HSDPA. Thisnew feature, (referred to hereinafter as “4DL-MIMO”), may have thepotential to not only provide doubled peak rates when compared toexisting specifications, but also improve spectral efficiency. Forexample, doubled peak rates may be up to 84 Mbps in a single carrier andpotentially up to 672 Mbps when 8 downlink carriers are usedsimultaneously.

FIG. 2 is an example of a conventional homogeneous network deployment.Each cell 201(a), 201(b), and 201(c) has its own network scheduler202(a), 202(b), and 202(c). Each WTRU 204(a), 204(b), and 204(c)receives a scrambling code 203(a), 203(b), and 203(c) from its ownnetwork scheduler 202(a), 202(b), and 202(c).

In a homogenous network deployment in a UMTS wireless cellular system,the radio equipment (RE), which includes the functionalities of thebaseband and layer 2 processing, may be co-located with the transmissionpoint, as shown in FIG. 2. Each cell may be associated with atransmission point that covers a geographic area where WTRUs in the areamay be served with data transmission scheduled by a network schedulerlocated in the RE. In order to improve the use of the frequencyspectrum, a frequency reuse factor of 1 may be adopted thereby allowingan adjacent cell to operate in the same frequency band. To assist theWTRU to identify a serving cell in the cell searching process andmitigate the inference from other cells, a unique scrambling code may beassigned to each cell that operates at the front end of the basebandprocess at the WTRU to suppress the signal from other cells. Commoncontrol physical channels (CCPCHs) may be broadcasted from each cell.The CCPCHs may carry important system configuration parametersassociated with a cell that may be uniquely identified by the WTRU usinga special scrambling code. The scrambling code may be used as a uniquecell ID for that cell in a UMTS system.

FIG. 3 is an example of a network deployment with RRH, wherein the RRHacts as an independent cell. Each cell 301(a), 301(b), and 301(c) hasits own network scheduler 302(a), 302(b), and 302(c). Each WTRU 304(a),304(b), and 304(c) receives a scrambling code 303(a), 303(b), and 303(c)from its own network scheduler 302(a), 302(b), and 302(c), respectively.Cells 301(b) and 301(c) include an RRH 305(b) and 305(c), respectively,each with their own REs 306 located in a centralized location, cell301(a).

By introducing RRH 305(b) and 305(c), the REs 306 may be separated fromthe transmission points, where the RRHs 305(b) and 305(c) are connectedto REs 306 by high speed and low latency backhaul links. Withoutchanging the cell configuration, a deployment strategy is illustrated inFIG. 3, where an RRH 305(b) or 305(c) may serve as a completelyindependent cell, identified by its own scrambling code that serves itsown scheduling area, though the REs 306 are centralized at differentlocations.

FIG. 4 is an example of utilizing common scrambling code (CSC) amongRRHs in UMTS. Cell 401(b) and 401(c) include an RRH 405(b) and 405(c),respectively, each with their own REs 406 located in a centralizedlocation, cell 401(a). All three cells 401(a), 401(b), and 401(c)utilize a common scrambling code (CSC) 403. Data may be transmittedsimultaneously from different transmission points to the same WTRU 404.

In order to improve the throughput performance for the WTRUs at the celledge and in order to enhance WTRU mobility, the concept of using commonscrambling code (CSC) 403 among the RRHs 405(b) and 405(c) may beimplemented as shown in FIG. 4.

A common scrambling code may be utilized among different RRHs using anyone or a combination of the following six techniques.

In a first technique, a common broadcast channel may be transmitted withthe same scrambling code. For example, a common broadcast channel may bea primary/secondary (P/S) CCPCH.

In a second technique, one or more physical channels may be similarlytransmitted across the RRHs, while the other may be different. Forexample, one or more physical channels may be a high speed-physicaldownlink shared channel (HS-PDSCH) and a high speed dedicated physicalcontrol channel (HS-DPCCH).

In a third technique, each RRH may be characterized as a single cell interms of scheduling and may have its own resource management thoughsharing the common scrambling code.

In a fourth technique, the schedulers in the CSC set may work jointly ina coordinated manner.

In a fifth technique, the cells in the CSC set may operate in the samefrequency.

In a sixth technique, each RRH may transmit with a differenttransmission power that may be dynamically changed.

Depending on various data scheduling options, a number of operationmodes with CSC may be used. The different operation modes are describedbelow.

FIG. 5 is an example of joint MP-HSDPA transmission mode. Cell 501(b)and 501(c) include an RRH 505(b) and 505(c), respectively, each withtheir own REs 506 located in a centralized location, cell 501(a). Allthree cells 501(a), 501(b), and 501(c) utilize a CSC 503. Each cell501(a), 501(b), and 501(c) has its own joint scheduler 502(a), 502(b),and 502(c). Data may be transmitted simultaneously from differenttransmission points to the same WTRU 504.

In a joint MP-HSDPA transmission, identical downlink signals carryingthe same data may be transmitted simultaneously from differenttransmission points to the same WTRU 504, as illustrated in FIG. 5.These signals may be combined over the air before arriving at the WTRUreceiver, so that the WTRU receiver perceives an enhanced signaloverall. The transmission mode may be of particular use for the WTRU atcell edge where the WTRU may suffer severe inter-cell interference. Allphysical channels, (P/S CCPCH, common pilot channel (CPICH), high speedshared control channel (HS-SCCH), HS-PDSCH, dedicated physical datachannel (DPDCH), and the like), may be transmitted this way. Because theWTRU is capable of performing channel state information (CSI) estimationand data demodulation based on the combined pilot signal carried by theCPICH, the WTRU may operate as if it is served by a single cell.

For joint MP-HSDPA transmission mode, the same data stream from a higherlayer may be transmitted to REs of each cell and the schedulers for thecells involved in the joint transmission may be operating jointly toschedule the same data to the WTRU. To further enhance the downlinktransmission reliability, different precoding weights may be appliedacross the transmission points to adjust the transmission phase or theamplitude individually. The selection of the precoding weights mayrequire the WTRU to distinguish the signal path from each transmissionpoint individually. Thus, the pilot may be identified for each cell andthe WTRU may measure preferred precoding weights and signal thepreferred precoding weights to the network via uplink feedback.

FIG. 6 is an example of multiflow aggregation to the same WTRUs. Cell601(b) and 601(c) include an RRH 605(b) and 605(c), respectively, eachwith their own REs 606 located in a centralized location, cell 601(a).All three cells 601(a), 601(b), and 601(c) utilize a CSC 603. Each cell601(a), 601(b), and 601(c) has its own joint scheduler 602(a), 602(b),and 602(c). Data may be transmitted simultaneously from differenttransmission points to the same WTRU 604.

In a mode of operation using multiflow aggregation to the same WTRUs,different data may be transmitted simultaneously from differenttransmission points to the same WTRU 604 as shown in FIG. 6. The WTRUmay demodulate the signals from each cell individually, and the datafrom each cell may be aggregated to get a higher throughput. Due tooperation in the same frequency and the same scrambling code for allcells involved in the multiflow transmission, and because of theinterference from other transmission points, it may be desirable tosuppress the interference at the WTRU demodulator. This issue may beeffectively resolved by exploring the spatial differences among thetransmission points and realizing the spatial multiplexing gain like aMIMO system does. Thus, the WTRU may be equipped with multiple antennasand a MIMO type of receiver structure.

For HSDPA transmission, high speed data may be transmitted via variousHS-PDSCHs from each transmission point with different transport blocksizes, or codeword sizes, which may be indicated to the WTRU by acorresponding HS-SCCH transmitted from that cell. The data stream may besplit and fed to each RE differently. The schedulers at each cell mayoperate independently to schedule the data simultaneously or atdifferent time instances. Alternatively, the schedulers may becoordinated to achieve a certain way of optimization, either in terms ofinterference reduction or other aspects.

Implementing the MIMO receiver may require the accurate estimation ofthe signal paths for each transmission point. Thus, distinguishablepilots or CPICHs may be designed for each transmission point to performthe channel estimation. As a more advanced option, the multiple dataflows may be processed by a precoding matrix and transmitted at eachtransmission point. This precoding matrix may be selected by the WTRUbased on the channel conditions of each signal path, or selected by thenetwork according to scheduling needs. As a result, a data flow may betransmitted across all the transmission points depending on theconfiguration of the precoding matrix.

In an example of the scheduling option, one data flow may be transmittedto a WTRU. However, this data transmission may be dynamically switchedamong the cells depending on the channel conditions. The schedulers mayjointly operate to select a transmission point based on signal quality.

FIG. 7 is an example of multiflow aggregation for single celltransmission to a single WTRU. Cell 701(b) and 701(c) include an RRH705(b) and 705(c), respectively, each with their own REs 706 located ina centralized location, cell 701(a). All three cells 701(a), 701(b), and701(c) utilize a CSC 703. Each cell 701(a), 701(b), and 701(c) has itsown network scheduler 702(a), 702(b), and 702(c). Each WTRU 704(a),704(b), and 704(c) receives a CSC 703 from its own network scheduler702(a), 702(b), and 702(c), respectively.

As shown in FIG. 7, a single cell transmission to a single WTRU issimilar to the aggregation transmission mode, except that multiple dataflows are transmitted from the multiple cells and the multiple dataflows are addressed to various WTRUs. Each WTRU may only need onereceiver to demodulate the data addressed to it. The HS-SCCH thatcarries the control information for the corresponding HS-PDSCH datatransmission may be identified by a unique ID of the receiving WTRU. TheWTRU may be equipped with multiple antennas and a MIMO receiver in orderto suppress the interference from other transmission points, or otherdata flows simultaneously transmitted in the same frequency and samescrambling code. This way of receiving data is similar to the concept ofmulti-user MIMO (MU-MIMO) in LTE, except that the data transmission isnow carried over multiple transmission points using the same scramblingcode. The advantage of this transmission mode is that it allows for thecell splitting gain to be realized thereby effectively improving theoverall system capacity.

The schedulers among the CSC set may work jointly to schedule the datato minimize cross interference between the WTRUs. The multiflowtransmission may also be processed by a precoding matrix beforetransmission. A data flow addressed to a WTRU may be associated to aspecific set of precoding weights, rather than a cell. The WTRU may berequired to report to the network its preferred precoding weights basedon a measured channel condition. For the purpose of reducing crossinterference, it may be desirable for the WTRU to select precodingweights based on the CSI for all the signal paths for the transmissionpoints involved in the transmission.

To support legacy WTRUs that are not designed for the CSC operation, anetwork scheduler may rely on available channel quality indicator (CQI)and precoding control indicator (PCI) information estimated by the WTRUto make scheduling decisions for transmissions. This does not requirethat the WTRU to be aware of the multipoint operation.

FIG. 8 is an example of 4 branch DL-MIMO operating at an individual RRH.Cell 802(b) includes an RRH 805 with its own RE 806 located in acentralized location, cell 801(a). RRH 805 includes multiple antennas810 which support multiple data streams 815.

As a more practical deployment scenario, as illustrated in FIG. 8, eachRRH may also include multiple antennas that may support multiple datastreams. In the single point multi-antenna transmission operation mode,4-branch DL-MIMO, each RRH, supported by its own scheduler, may beconsidered as an independent single point transmission operation withdownlink MIMO with more than two layers.

FIG. 9 is an example of 4 branch DL-MIMO when RRHs are used as simpleantenna extensions. Cell 901 includes RRHs 905(a), 905(b), and 905(c).RRHs 905(a), 905(b), and 905(c) utilize common network scheduler 902.

In a similar deployment scenario, the antennas of the RRHs are may beconsidered as the antenna extension of the primary base station shown inFIG. 9. Here, additional schedulers associated with the individual RRHsmay not be needed. Therefore, the combination of the primary basestation and the RRHs may include a common scheduling area. The 4DL-MIMOdesign may also include a design where the antennas are co-locatedwithin the base station with optional RRH deployment.

A similar concept of same cell ID with RRH configurations is proposed inLTE coordinated multipoint (CoMP) and may be extended to HSDPA in theUMTS cellular network. As a proposed embodiment, a common scramblingcode may be shared among the cells connected with RRH in order toimprove the WTRU mobility and enhance the coverage of the controlsignals.

Pilot design may be introduced to multiple downlink antennas,specifically 4DL-MIMO, and the RRH deployment to HSDPA, as there areonly two pilots in existing DL-MIMO that may support up to rank 2transmission. Further, while the concepts described herein are describedin the context of 4 DL antennas, the concepts may also be applied toother antenna configurations, for example, 8 or more DL antennas.Therefore, when referring to 4-branch MIMO operations, it should beunderstood that this also refers to more than 4-branch operations, (e.g.8-branch MIMO operations).

The CPICH is a common pilot channel designed in UMTS to aid the channelestimation at the WTRU for downlink data transmissions. The CPICH may bescrambled with a unique scrambling code for each cell. Therefore, theCPICH may be considered to be cell-specific. New types of pilot channelsmay be used to accommodate different transmission modes in the CSCoperation.

A common pilot channel is a pilot channel transmitted from all thetransmission points and may be scrambled with a scrambling code used inthe CSC operation. The common pilot channel may be received by all ofthe WTRUs being served in the CSC area. A P-CPICH may be used that has aslot format of 20 bits/slot and a modulating bit sequence of all 0s, maybe directly used for this purpose. Optionally, other modulating bitsequences may be used to differentiate the CSC operation.

When REs are not co-located with the transmission points, advancedtiming adjustment may be required for the baseband processing occurringat REs to ensure that the signals from each of the transmission pointsare accurately synchronized. Because this common pilot channel isintended to serve all of the WTRUs in an area, no cross-site precodingweights may be applied to the common pilot channel, in case otherphysical channels are precoded for performance enhancement.

For the joint transmission mode, the common pilot channel may besufficient for the WTRU to perform channel estimation and to demodulatethe data, if no cross-cell precoding is employed.

In a cell-specific or transmission-point specific pilot channel, eachcell may transmit a pilot channel distinguishable from other cells. Thecell-specific pilot channel may be designed to allow a WTRU to performchannel estimation for each individual signal path to the transmissionpoints. Therefore, the cell-specific pilot channels may be orthogonal orclose to orthogonal to single out the desired signal for the channelestimation.

The orthogonality of the cell-specific pilot channels may be maintainedby using an orthogonal modulating bit sequence. The bit sequences fedinto the modulation mapped may be pre-defined differently for each ofthe cell-specific pilot channels. These bit sequences may be selectedfrom a pool of orthogonal binary sequences of the similar slot format ofCPICH. Table 1 is an example of orthogonal binary bit sequence used inthe pilot channel.

TABLE 1 even bit sequence 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 bitsequence 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 bit sequence 1 1 0 0 11 0 0 1 1 0 0 1 1 0 0 1 1 0 0 bit sequence 1 1 1 1 0 0 0 0 1 1 1 1 0 0 00 1 1 1 1 odd bit sequence 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 bitsequence 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 bit sequence 1 1 0 0 11 0 0 1 1 0 0 1 1 0 0 1 1 0 0 bit sequence 0 0 0 0 1 1 1 1 0 0 0 0 1 1 11 0 0 0 0As shown in Table 1, the binary bit sequences may have a patterndefined, where the length of the sequence covers two time slots. Bitsequences of longer length (such as 4 or 8 slots) may also be used,which may generate more orthogonal choices. Use of an orthogonalsequence by the CSC cells may be assigned by a UTRAN, and indicated to aNode-B and a WTRU at a radio resource control (RRC) configuration. Forexample, the Node-B and WTRU may be informed of the orthogonal sequencevia dedicated signaling or system information blocks (SIBs).

The orthogonality of the cell-specific pilot channels may be maintainedby using different channelization codes. With a spreading factor madeequal to 256, (same as the CPICH), different channelization codes may beapplied to the cell-specific pilot channels. As the channelization codesare orthogonal by nature, the pilot channels may be orthogonal from eachother. For example, channelization codes, C_(256,2) and C_(256,3) may becandidates for the new pilot channels. The WTRU may obtain thechannelization code and pilot information via dedicated RRC signaling orvia the SIBs. Alternatively, the actual channelization codes used andpilot patterns may be pre-defined.

The orthogonality of the cell-specific pilot channels may be maintainedby using different scrambling codes. The cell-specific pilot channelsmay be transmitted differently by each cell under a different scramblingcode. Although the pilot channels may not be perfectly orthogonal, theresidual may be small enough to carry out the channel estimation at theWTRU receiver. Use of orthogonal sequences by the CSC cells may beassigned by a UTRAN, informed to a Node-B and a WTRU at an RRCconfiguration.

The orthogonality of the cell-specific pilot channels may be maintainedby time division multiplexing (TDM) the pilot channels. The transmitpoints in the CSC set may be coordinated in transmitting the pilotchannel in a time switched manner, using the same bit sequence,channelization code, and scrambling code. As long as the network informsthe WTRU of the schedule of the pilot channel transmission, the WTRU mayperform individual channel estimation for a cell for the specifiedduration.

The orthogonality of the cell-specific pilot channels may be maintainedby overhead reduction. Introducing additional pilot channels mayincrease the control channel overhead and thus reduce efficiency of thedata transmission. To mitigate the impact, a gated transmission may beadopted that only allows the transmission to take place within aspecified duty cycle. In addition, the transmit power of thecell-specific pilot channel may be scaled down. In such cases, the WTRUmay be informed of the power difference between the primary CPICH andthe other pilot(s) via RRC signaling. This may allow the WTRU tocompensate for the difference in transmission power in order to estimatethe true channel.

The CPICH is a common pilot channel designed in UMTS to aid the channelestimation at the WTRU for downlink data transmission. In 2-Tx DL MIMO,each antenna may have a common pilot channel so that the WTRU maycompute the channel estimate for the antenna. This concept may beextended to 4-Tx DL MIMO, or more antennas, with a separate common pilotchannel for each antenna. When 4-Tx DL MIMO is supported, the fourcommon pilot channels may be transmitted and used for both datademodulation and measuring CSI. A similar concept may apply when morethan 4 antennas are configured.

Each of the CPICHs may be spread using a unique channelization code.Since the channelization codes are orthogonal, the WTRU may be able todetermine unique channel estimates for each antenna. However, this mayreduce the number of available codes for other physical channels andcode usage may be an issue.

To avoid any issues related to code usage, each CPICH may transmit anorthogonal pilot sequence and use the same channelization code. This maybe used in various combinations of channelization codes and orthogonalpilot sequences. For example, in 4-Tx DL MIMO, each CPICH may transmitan orthogonal pilot sequence, and all four CPICHs may be spread with thesame channelization code (e.g., C_(256,0)), or two orthogonal pilotsequences and two different channelization codes.

Another potential issue related to using one CPICH per antenna is thepresence of increased control channel overhead. To reduce the impact ofadditional CPICHs, the Node-B may periodically transmit the new CPICHsand/or transmit them at a lower power than the legacy CPICHs. When thenew CPICHs are transmitted at a lower power, they may be used for CSImeasurements. If the new CPICHs are needed for data demodulation, theNode-B may increase the power on the new CPICHs. However, the WTRU mayneed to know the change in CPICH power when it occurs for accurate CSImeasurements. Also, increasing the CPICH power may increase the interNode-B interference and may require additional pilot interferencecancellation at the WTRU.

Common pilot design considerations may be made for co-scheduled 4-branchMIMO and legacy 2-branch MIMO systems. When downlink (2-branch) MIMO isconfigured, the two pilot channels P-CPICH and S-CPICH may use twodifferent channelization codes. When 4-branch MIMO is configured,although it may be challenging to co-schedule a 4-branch MIMO WTRU, thelegacy WTRU may use 4 physical antennas by using a virtual antenna, a4-branch MIMO WTRU and a 2-branch WTRU that use only 2 physical antennasmay be co-scheduled. Therefore, it may be beneficial to keep the P-CPICHand S-CPICH pilot channel setting the same as the one required by legacy2-branch MIMO when 4-branch, or more, MIMO is configured. Consequently,for the 4-branch MIMO case, the third and fourth common pilots CPICH3and CPICH4 may share the two channelization codes with the P-CPICH andS-CPICH, while the pilot bit patterns may be orthogonal to the one usedin P-CPICH and S-CPICH as shown in FIG. 10. FIG. 10 is an examplemodulation pattern and channelization code assignment for four commonpilot channels. The four common pilot channels in FIG. 10 are P-CPICH1001, S-CPICH 1002, CPICH3 1003, and CPICH4 1004. P-CPICH 1001 andCPICH3 1003 share channelization code A. S-CPICH 1002 and CPICH4 1004share channelization code B.

Instead of sharing the P-CPICH and S-CPICH pilot channels between4-branch MIMO WTRUs and legacy 2-branch MIMO WTRUs, another example maybe to introduce four new common pilot channels, on top of the existingP-CPICH and S-CPICH pilot channels. The benefit of this pilotconfiguration scheme is that the legacy 2-branch MIMO WTRUs may beco-scheduled with 4-branch MIMO WTRUs, and the legacy 2-branch MIMOWTRUs may make full use of the four physical transmit antennas at thesame time. If the four new common pilot channels are labeled as CPICH1,CPICH2, CPICH3, and CPICH4, the configuration of P-CPICH and S-CPICH maybe the same as for the legacy 2-branch MIMO WTRUs as shown in FIG. 10.

FIG. 11 is a first example modulation pattern and channelization codeassignment for six common pilot channels. The 6 common pilot channels inFIG. 11 are P-CPICH 1101, S-CPICH 1102, CPICH1 1103, CPICH2 1104, CPICH31105, and CPICH4 1106. CPICH1 1103 and CPICH2 1104 share channelizationcode C. CPICH3 1105 and CPICH4 1106 share channelization code D. Theorthogonality between CPICH1 and CPICH2 and the orthogonality betweenCPICH3 and CPICH4 may be guaranteed by applying two orthogonal pilotpatterns, as shown in FIG. 11.

FIG. 12 is a second example modulation pattern and channelization codeassignment for six common pilot channels. The 6 common pilot channels inFIG. 12 are P-CPICH 1201, S-CPICH 1202, CPICH1 1203, CPICH2 1204, CPICH31205, and CPICH4 1206. To save the usage of DL channelization codes, thenew four common pilot channels CPICH1 1203 and CPICH2 1204, CPICH3 1205and CPICH4 1206 share the same channelization code C, while theorthogonality among the four new pilot channels may be kept by usingorthogonal pilot sequences as shown in Table 1.

The WTRU-specific pilot channel may be generated in a similar way as thecell-specific pilot channel. The difference between the WTRU-specificpilot channel and the cell-specific pilot channel is that theWTRU-specific pilot channel is introduced to serve a specific WTRU orspecific group of WTRUs. Therefore the WTRU-specific pilot channel maybe precoded with the precoding weights obtained from the channelconditions for that WTRU. The WTRU-specific pilot channel may betransmitted from one cell or jointly transmitted from multiple cells.For data demodulation, one pilot per stream may be needed, whereas forCSI reporting purposes, one pilot per antenna may be required.

For example, for every scheduled 4-branch MIMO WTRU, up to 4WTRU-specific pilot channels may need to be transmitted, and 4 newcommon pilot channels may also be needed for CSI feedback generation for4-branch MIMO WTRUs in order to make the 4-branch MIMO fully transparentto legacy 2-branch MIMO WTRUs so that 4-branch MIMO WTRUs and 2-branchMIMO WTRUs may be co-scheduled in the same subframe. However, this mayrequire a significant amount of channelization codes in the downlink ifcode multiplexing pilot channels are based on channelization codes. Forthe 4 new common pilot channels, the channels may be transmitted with alower duty cycle than WTRU-specific pilot channels, and therefore theymay be transmitted in a time multiplexing fashion so that the channelsmay share a common channelization code.

Several of the embodiments described below may significantly reduce theamount of required channelization codes for transmission ofWTRU-specific pilot channels.

A first family of separate channelization code (code divisionmultiplexed (CDM)) solutions may consist of the WTRU receiving the pilotsymbols over a separate channelization code. In one embodiment, allWTRU-specific pilot channels may be transmitted over one commonchannelization code such that the WTRU-specific pilot channels may beorthogonal to all other legacy downlink channels, such as P-CPICH,S-CPICH, and HS-PDSCH, and the like. Orthogonality of the WTRU-specificpilots within each WTRU, and orthogonality of the WTRU-specific pilotsamong different WTRUs may be achieved by using orthogonal pilotsequences under the same channelization code. In this embodiment, apilot resource may be uniquely identified by a (RRC configured, static)channelization code and a pilot sequence index. Using a staticchannelization code, the WTRU may only need to be signaled by the pilotsequence index on a dynamic basis.

In another embodiment, for all 4-branch MIMO WTRUs that are co-scheduledwithin one subframe, the WTRU-specific pilot channels belonging to thesame WTRU may share one common channelization code that is associatedwith that WTRU. The orthogonality of WTRU-specific pilot channels amongdifferent WTRUs may be achieved by applying different channelizationcodes to different WTRUs that are co-scheduled in the same subframe.This embodiment may be appropriate for the case where the number of theco-scheduled 4-branch MIMO WTRUs is not significant. The benefit of thisembodiment is that four orthogonal pilot sequences are sufficient andthere may be no need to signal the WTRU with pilot sequences that areused by the Node-B. A set of predefined pilot sequences may be used forall WTRUs. In such cases, while each pilot resource may consist of apair of channelization code index and pilot sequence index, only thechannelization code (and the transmission rank) may be dynamicallysignaled to the WTRU.

In another embodiment, the multiple WTRU dedicated pilot sequences maybe transmitted by the Node-B and received by the WTRU using acombination of channelization codes and pilot sequences. Thus each pilotresource consists of a pair of channelization code index and pilotsequence index.

In an example of this embodiment, a fixed number of pilot sequences aredefined and may be re-used for each channelization code. Thus the totalnumber of pilot resources is given by the product of the number ofchannelization codes and the defined pilot sequences.

In another embodiment, the WTRU may receive a list of channelizationcode resources for dedicated pilots via RRC signaling. The pilotresources may then be organized for indexing in order of channelizationcode list and pilot sequence indices for each channelization code. Table2 is an example of pilot resource indexing.

TABLE 2 Channelization code Pilot sequence Pilot resource index CC #0Sequence #0 0 Sequence #1 1 . . . 2 Sequence #(N_(seq) − 1) 3 CC #1Sequence #0 4 Sequence #1 5 . . . 6 Sequence #(N_(seq) − 1) 7 . . . . .. . . . CC #(N_(cc) − 1) Sequence #0 (N_(cc) − 1) * N_(seq) + 1 Sequence#1 . . . . . . . . . Sequence #(N_(seq) − 1) Ncc * N_(seq) − 1Table 2 shows an example of how pilot resources may be indexed when acombination of multiple channelization codes and pilot sequences areavailable. Here, N_(cc) is the number of channelization codes signaledby the network and N_(seq) is the maximum number of pilot sequencessupported for a single channelization code. For example, the maximumnumber of pilot sequences supported for a single channelization code maybe pre-defined in the specifications or configured by RRC signaling.

In one case of the embodiment described above, Nseq=1 and eachchannelization code may carry only 1 pilot sequence. In another case ofthe embodiment described above, Ncc=1 and thus all the pilots sequencesmay be carried using a single channelization code.

To reduce the signaling load associated to populating this list, a setof rules may be implemented such that the pilot resource indices are notnecessarily signaled but rather inferred from the RRC signal orderedlist. For example, the pilot resource indices may be inferred based onthe order of the signaled pilot resource information. In one example,the WTRU is signaled a list of dedicated pilot channelization codes viaRRC signaling. Based on the knowledge of Nseq, either fixed in thespecifications or signaled by the network, (e.g., also via RRCsignaling), the WTRU may determine the pilot resource indices in theorder of the channelization code list received via RRC signaling.

Depending on the method used for transmission of a dedicated pilot, anumber of approaches may be used for the WTRU to determine the pilotresource to use for the associated data transmission. It may bedesirable to have a small signaling overhead while leaving sufficientflexibility to allocate the resources efficiently.

The methods for determining pilot information may be categorized as“implicit” and “explicit” indication methods. The methods may be usedwith any applicable dedicated pilot resource allocation method in anyorder or combination.

When using implicit indication methods, it may be assumed that noadditional signaling is required and it may be assumed that the WTRUdetermines the pilot information for each data stream based on fixedrules.

In one particular method of implicit indication, the WTRU may beconfigured via RRC dedicated signaling with a specific dedicated pilotresource or a set of resources linked to one or more HS-SCCH resource orHS-SCCH number configured for dedicated pilot use. When the WTRU detectsits high speed downlink shared channel (HS-DSCH) radio networktransaction identifier (H-RNTI) on one of the configured HS-SCCHresources, the WTRU may determine the pilot information for theassociated HS-PDSCH by association with the HS-SCCH configuration.

In an example of this method, the WTRU may be pre-configured with a setof pilot sequences. For example, the WTRU may be pre-configured with upto the maximum of layers supported. The WTRU may receive an RRCconfiguration for HSDPA with dedicated pilots. For each HS-SCCH resourceindicated, the WTRU may also receive the associated pilot channelizationcode. In another example, the pilot channelization code may be indicatedunder the “HS-SCCH Channelization Code” IE in the “HS-SCCH Info” IE asspecified in the RRC specifications. When the WTRU detects its H-RNTI inthe HS-SCCH, the WTRU may determine the pilot resources by associationwith the HS-SCCH number or resource. More specifically, when the WTRUdetects its H-RNTI on a specific HS-SCCH resource, the WTRU maydetermine the associated HS-SCCH number from the IE configuration indexassociated with that HS-SCCH resource. The number of pilots may bedetermined explicitly or based on a combination of the number oftransport blocks or codewords and associated layers as signaled on theHS-SCCH, for example. Hereinafter transport block and codewords are usedinterchangeably.

In another example of this method, the WTRU may be pre-configured with aset of pilot resources, which may be indexed sequentially (for example,see Table 2). The WTRU may receive an RRC configuration for HSDPA withdedicated pilots. For each HS-SCCH resource indicated, the WTRU may alsoreceive a base pilot resource index. When the WTRU detects its H-RNTI inthe HS-SCCH, the WTRU may determine the pilot resource information,(channelization code, pilot sequences), by using the pilot resourceindex associated to the HS-SCCH number or resource in the configuredlook-up table.

Using the implicit approach with the HS-SCCH number/resource may havethe advantage of the WTRU knowing the pilot resource before starting toreceive the HS-PDSCH.

When using explicit methods, the WTRU may be indicated explicitly by theNode-B which dedicated pilot resource(s) to use for the associatedHS-PDSCH transmission.

In an example of this method, the WTRU may receive the dedicated pilotresource information in part 1 of the HS-SCCH. For example, thededicated pilot resource information may consist of one or more indicesto pilot resources. In another example, the dedicated pilot resourceinformation may consist of a single index indicating a dedicated pilotchannelization code or an index to a dedicated pilot channelizationcode, in which case the WTRU may determine the set of dedicated pilotsresources to use by using a known pre-defined set of pilot sequences andthe number of layers as signaled or determined from other fields in theHS-SCCH. This may be appropriate, for example, when a singlechannelization code per WTRU is used for dedicated pilot transmission.Alternatively, this dedicated pilot resource information may consist ofa single index indicating, for example, a base pilot resource index, inwhich case the WTRU may determine the set of dedicated pilot resourcesto use via a configured look-up table and the number of layersdetermined for example using the other fields in the HS-SCCH.

In the following example, up to 4 pilots may be needed for rank-4transmission, up to 4 sets of pilot information need to be signaled.This may be achieved for example by signaling a starting index of a setof orthogonal pilot sequences, and the WTRU may derive the numbers orindices of the rest of pilot sequences by reading the rank informationsignaled from the Node-B. This approach may require that the Node-B usea consecutive pilot index or that a fixed rule is defined for the WTRUto determine the pilot indices, and that both the WTRU and the Node-Bare aware of the list of pilot indices. Alternatively, the Node-B maysignal both the starting index of a set of orthogonal pilot sequencesand the number of the orthogonal pilot sequences to be used by thatWTRU. In this case, the number of the orthogonal pilot sequences mayalso be used as a rank indication. Therefore, there may not be a needfor the Node-B to signal additional rank information to the WTRU.

FIG. 13 is an example of pilot indexing with rank indication. FIG. 13includes pilot 1301. A starting point 1305 indicates starting with pilot1301(a). The rank information 1310 is used by the WTRU for demodulationand indicates that pilots 1301(a) through 1301(b) should be used for thedemodulation.

FIG. 13 illustrates an example where N is the maximum available numberof orthogonal pilot resources. In the example, the WTRU may indicate astarting index pointing to Pilot #1 and a rank information of 3 layersleading the WTRU to use pilot indices #1-3 for demodulation of the threelayers. A wrap-around of the indices may also be used. This example maybe extended to support more than rank-4 transmission where the Node-Band the WTRU support a larger number of antennas.

After receiving the HS-SCCH, the WTRU may determine the number oftransport blocks in the associated HS-PDSCH, and the number of layersfor each transport block. The number of layers for each transport blockmay be determined by a combination of fixed rules and explicitinformation signaled on the HS-SCCH.

In one example, each transport block may be limited to a single layer bythe specifications. Then, there is a one-to-one mapping between thenumber of transport blocks and the number of layers. The WTRU mayreceive the information on the number of transport blocks or number oflayers in the HS-SCCH (preferably in part 1).

The WTRU may then associate each transport block, with the informationsignaled in the HS-SCCH, to a given layer in order of the dedicatedpilot index, (for example as configured via RRC signaling or in thespecifications). For example, the WTRU may be configured with a set ofpilot resources, for example via RRC configuration. In one particularexample, the pilot resource configuration may consist of a startingindex to a table of pilot resources. Then a given transmission timeinterval (TTI) the WTRU may be indicated via the HS-SCCH that theHS-PDSCH carries N layers. The WTRU may further determine theassociation between each layer and pilot based on the number of layersand the pilot resource configuration. For example, layer 1 may beassociated to the first pilot in the set, layer 2 to the second pilot inthe set and so forth.

In another example, each transport block may be carried using more thanone layer. The actual transport configuration may be restricted by thespecifications.

Table 3 is an example of transport blocks to number of layer mappingwith up to 4 simultaneous transport blocks.

TABLE 3 Config # Nb of layers Nb of TB Nb of layers for each TB 1 1 1 12 2 1 2 3 2 1, 1 4 3 1 3 5 2 2, 1 5A 3 1, 1, 1 6 4 1 4 7 2 3, 1 8 2 2, 28A 3 2, 1, 1 8B 4 1, 1, 1, 1Table 3 includes a table that lists a number of possible transportconfigurations or transport blocks to number of layer mapping with up to4 simultaneous transport blocks. In practice, the set of configurationssupported may be smaller than what is listed in Table 3.

In one practical example or configuration reduction, the WTRU may belimited to two transport blocks at each TTI, and each transport blockmay thus be carried by up to two layers. Table 4 is an example of areduced configurations set for up to two simultaneous transport blockswith up to 4 layers.

TABLE 4 Nb of layers for each TB Config # Nb of layers Nb of TB L₁, L₂ 11 1 1, 0 2 2 2 1, 1 3 3 2 1, 2 4 4 2 2, 2Table 4 illustrates an example of this concept, derived from Table 3,where only 4 transmission configurations are supported. The number oflayers for the first and second transport block (L₁, L₂, respectively)is shown in the last column.

In another example, up to two transport blocks may be multiplexed into asingle code word. In this example, a codeword is not necessarilyidentical to a transport block. Codewords containing a single transportblock may be transmitted with a single layer, whereas codewordscontaining two transport blocks may be transmitted using two layers. Inthe context of 4DL-MIMO, the WTRU may be configured to receive up to 2codewords.

In this example, the WTRU may be indicated the number of transportblocks or codewords and number of layers in the HS-SCCH, preferably inpart 1. The WTRU may then associate each transport block to one or twolayers in the order of dedicated pilot index. This association may becarried out by the WTRU using a table lookup, for example.

In one example, the WTRU may determine the number of transport blocksbased on the indicated number of codewords and number of layers in theHS-SCCH, preferably part 1 using a fixed set of rules.

More generally, it may be assumed that the WTRU is configured with a setof dedicated pilots that may be indexed. This indexing may be achievedusing, for example, any one or a combination of the methods describedabove. Then let p_(l,k) be the dedicated pilot index associated to layerindex k=0,1, . . . , N_(L) of transport block index l=0,1, . . . ,N_(tb), where N_(L) and N_(tb) are the maximum number of layers pertransport block and the maximum number of simultaneous transport blocksfor a subframe. Further it may be assumed that the WTRU dynamicallyreceives a dedicated pilot base index offset b.

In one embodiment, the pilots may be associated in order of transportblock first and then layers for each transport block. For example, whentwo transport blocks are transmitted, each with two layers, the firstand second dedicated pilots for that WTRU may be associated with thefirst and second layers of the first transport block, respectively, andthe third and fourth dedicated pilots may be associated with the firstand second layers of the second transport block, respectively.

In this example approach, the dedicated pilot index associated to thelayer l or transport block k may be expressed as:

p _(l,k) =b+l+N _(L) ×k.   Equation (1)

This expression may imply that the maximum number of layers is allocatedto the first block before another transport block can be allocated alayer. Alternatively, the number of the layer for transport block k maybe expressed as N_(L,k), and the following expression for the pilotindex does not suffer from that restriction:

$\begin{matrix}{p_{l,k} = {b + l + {\sum\limits_{j = 0}^{k - 1}\; N_{L,j}}}} & {{Equation}\mspace{14mu} (2)}\end{matrix}$

Alternatively in another approach, the pilots may be associated first inorder of layers for each transport block. For example, when twotransport blocks are transmitted, each with two layers, the first andsecond dedicated pilots for that WTRU may be associated with the firstlayer of the first and second transport block, respectively. The thirdand fourth dedicated pilots may be associated with the second layer ofthe first and second transport block, respectively.

Similarly in this example approach, the dedicated pilot index associatedto the layer l or transport block k may be expressed as:

p _(l,k) =b+k+N _(tb) ×l.   Equation (3)

This expression may ensure that the layers are allocated to each TB inturn. Finally, for convenience, wrap around of the dedicated pilotindices may also be used, and in such cases the actual index p_(l,k)′may be determined via a modulo operation, for example as follows:

p _(l,k) ′=p _(l,k) mod N _(tb) ×N _(L).   Equation (4)

In another embodiment, the WTRU-specific pilots may be time-multiplexedwith an HS-PDSCH channel. FIG. 14 is an example of time multiplexingWTRU-specific pilot with HS-PDSCH. FIG. 14 includes slot #0 1401(a),slot #1 1401(b), and slot #2 1401(c). Slot #1 1401(b) is expanded toshow that it includes data 1405 and a pilot 1410. The pilot 1410 isinserted into the middle of slot #1 1401(b). FIG. 14 illustrates anexample where the pilots are inserted into the middle of each slot of anHS-PDSCH subframe.

Since multicode transmission is possible, where multiple channelizationcodes may be assigned to a single WTRU for HS-PDSCH transmission, theWTRU-specific pilots may need to be transmitted on one of the assignedchannelization codes, as shown in FIG. 15, while the HS-PDSCH channelson other assigned channelization codes are transmitted in the legacyway. FIG. 15 is an example of time multiplexing WTRU-specific pilot withHS-PDSCH on one channelization code. FIG. 15 illustrates channelizationcode #1 1520 to code #15 1530. In channelization code #1 1520, slots #01501(a), #1 1501(b), and #2 1501(c) include pilot 1510 inserted betweendata 1505 of an HS-PDSCH subframe. Channelization code #2 1525 to code#15 1530 only include data 1505 in each HS-PDSCH subframe.

Alternatively, the WTRU-specific pilots may be transmitted on one of theassigned channelization codes, and the pilot portion of HS-PDSCHs onother assigned channelization codes are not transmitted ordiscontinuously transmitted (DTXed), as shown in FIG. 16. FIG. 16 is anexample of time multiplexing WTRU-specific pilot with HS-PDSCH on onechannelization code and discontinuously transmitting the pilot portionof HS_PDSCHs on all other channelization codes. FIG. 16 illustrateschannelization code #1 1620 to code #15 1630. In channelization code #11620, slots #0 1601(a), #1 1601(b), and #2 1601(c) include pilot 1610inserted between data 1605 of an HS-PDSCH subframe. Channelization code#2 1625 to code #15 1630 includes a discontinuous transmission (DTX)1615 inserted between data 1605 in each HS-PDSCH subframe.

Alternatively, the WTRU-specific pilot may be time multiplexed with theHS-PDSCH on each assigned channelization code, as shown in FIG. 17. FIG.17 is an example of time multiplexing WTRU-specific pilot with HS-PDSCHon all assigned channelization codes (up to 15). FIG. 17 illustrateschannelization code #1 1720 to code #15 1730. In channelization code #11720 to code #15 1730, slots #0 1701(a), #1 1701(b), and #2 1701(c)include pilot 1710 inserted between data 1705 of an HS-PDSCH subframe.

Alternatively, the pilot symbols may be spread uniformly across theradio slot in the HS-PDSCH on one code or over all channelization codes.Any number of pilot symbols (N_(pilot)) may be inserted in a givenHS-PDSCH radio slot.

Table 5 is an example of traffic-to-pilot ratio for various numbers ofpilot symbols per radio slot.

TABLE 5 Nb pilots symbols/slot T/P (dB) 1 22.0 2 19.0 3 17.2 4 15.9 514.9 6 14.1 7 13.4 8 12.8 9 12.2 10 11.8 11 11.3 12 10.9 13 10.5 14 10.215 9.9 16 9.5 17 9.2 18 9.0 19 8.7 20 8.5Table 5 shows the resulting traffic-to-pilot power ratio (T/P) for eachvalue of number of pilots (for 1 radio slot) in a spreading factor(SF)=16 HS-PDSCH. Nb pilot symbols, 4, 5, 6, 8, 9, 12, and 15 areentries that correspond to one example subset of values that may beused. These values were obtained by finding the entries corresponding to10,11,12, . . . 16 dB T/P as it is currently defined for the uplink. Thevalues are for a single radio-slot for a single code. To achieve thelisted T/P the corresponding number of pilots must be inserted on eachchannelization code and for all slots in the subframe.

As it may be more convenient in terms of hardware processing to have allthe pilot symbols carried on a single channelization code (asillustrated by FIG. 17), the number of pilot symbols present on thechannelization code carrying pilot may depend on the actual number ofHS-PDSCH codes being used for the transmission. In one method, the WTRUmay be configured, for example, via RRC signaling for a specific T/P.Then, assuming the same pilot power and modulation scheme for allsymbols in a HS-PDSCH code, the WTRU may determine the actual number ofpilots used.

For example, assuming that N_(ch) HS-PDSCH codes are being used (Nch=1,. . . , 15), then the WTRU may determine the number of pilot symbolsN_(pilot) (for one radio slot) on the HS-PDSCH code carrying the pilotsymbols via this expression:

$\begin{matrix}{{N_{piolt} = \left\lfloor \frac{N_{ch} \times 160}{1 + 10^{{TP}/10}} \right\rfloor},} & {{Equation}\mspace{14mu} (5)}\end{matrix}$

where 160 corresponds to the number of SF=16 symbols in one radio slot,and TP is the T/P expressed in dB. While a floor operation is indicatedin Equation (5), a ceiling or rounding up to the closest integer mayalso be used to determine the number of pilot symbols.

The WTRU may also be configured with a fixed table indicating the numberof pilot symbols for each possible configuration of T/P and number ofHS-PDSCH codes being transmitted. Table 6 is an example table of thenumber of pilots for each T/P and number of HS-PDSCH codesconfiguration.

TABLE 6 Number of HS-PDSCH codes 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 T/P10 14 29 43 58 72 87 101 116 130 145 160 X X X X (dB) 11 11 23 35 47 5870 82 94 105 117 129 141 X X X 12 9 18 28 37 47 56 66 75 85 94 104 113123 132 142 13 7 15 22 30 38 45 53 61 68 76 83 91 99 106 114 14 6 12 1824 30 36 42 49 55 61 67 73 79 85 91 15 4 9 14 19 24 29 34 39 44 49 53 5863 68 73 16 3 7 11 15 19 23 27 31 35 39 43 47 50 54 58Table 6 shows an example of such a configuration table, (obtained usingEquation (5)). The entries designated with an “X” may require more pilotsymbols than what is available using a single code, and thereby may notbe used. Optionally, for those entries, the WTRU may be configured totransmit using the maximum number of pilot symbols (i.e., 160).

The network may also signal the power ratio between the WTRU-specificpilot channel and the data channel (HS-PDSCH) to the WTRU. This may becarried out, for example, via RRC signaling or other means. To assistCQI evaluation at the WTRU, one or any combination of the followingpower ratios may be signaled from the Node-B to the WTRU via RRCsignaling: the ratio between common pilot power and WTRU specific pilotpower, the ratio between WTRU specific pilot power and data power, andthe ratio between common pilot power and data power.

The construction of orthogonal pilot sequences for WTRU-specific pilotchannels may depend on the spreading factor selected. If the spreadingfactor is 256, the pilot sequences shown in Table 1 for a common pilotchannel may be reused. If a spreading factor of 128 is chosen, thefollowing approach may be used to construct a set of orthogonal pilotbit sequences with bit length of 40:

$\begin{matrix}{{P = \begin{bmatrix}A & A & B & C \\{- B} & {- C} & A & A \\{- A} & A & C & {- B} \\{- C} & B & {- A} & A\end{bmatrix}};} & {{Equation}\mspace{14mu} (6)} \\{where} & \; \\{{A = \begin{bmatrix}{- 1} & 1 & 1 & 1 & 1 \\1 & {- 1} & 1 & 1 & 1 \\1 & 1 & {- 1} & 1 & 1 \\1 & 1 & 1 & {- 1} & 1 \\1 & 1 & 1 & 1 & {- 1}\end{bmatrix}};} & {{Equation}\mspace{14mu} (7)} \\{{B = \begin{bmatrix}1 & {- 1} & 1 & 1 & {- 1} \\{- 1} & 1 & {- 1} & 1 & 1 \\1 & {- 1} & 1 & {- 1} & 1 \\1 & 1 & {- 1} & 1 & {- 1} \\{- 1} & 1 & 1 & {- 1} & 1\end{bmatrix}};} & {{Equation}\mspace{14mu} (8)} \\{and} & \; \\{{C = \begin{bmatrix}1 & 1 & {- 1} & {- 1} & 1 \\1 & 1 & 1 & {- 1} & {- 1} \\{- 1} & 1 & 1 & 1 & {- 1} \\{- 1} & {- 1} & 1 & 1 & 1 \\1 & {- 1} & {- 1} & 1 & 1\end{bmatrix}},} & {{Equation}\mspace{14mu} (9)}\end{matrix}$

where 1 is mapped to binary bits 00 and −1 is mapped to binary bits 11.The binary bits may be used for modulation symbol mapping.

If the spreading factor is 4, a set of four orthogonal pilot symbolswith length of 4 may be defined as follows:

$\begin{matrix}{{P_{4} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & 1 & {- 1} & {- 1} \\1 & {- 1} & 1 & {- 1} \\1 & {- 1} & {- 1} & 1\end{bmatrix}},} & {{Equation}\mspace{14mu}\lbrack 10\rbrack}\end{matrix}$

where each row represents one pilot pattern and 1 is mapped to binarybits 00 and −1 is mapped to binary bits 11. Consequently, the length ofthe corresponding pilot bit sequence is 8. This 4-symbol long pilot maybe used to construct an 8-symbol pilot, which is defined as follows:

P₈=[P₄ P₄].   Equation (11)

A network may also take advantage of multiple downlink transmit antennasto increase the coverage of control channels. Further, pre-coding orbeamforming may be applied to the HS-SCCH in order to increase HS-DSCHcoverage, reduce interference, and use less power resources for thatparticular control channel.

Methods for the WTRU to receive, demodulate, and decode the precodedcontrol channel information, for example, HS-SCCH, are described in thecontext of both pre-coded pilot and common pilot scenarios below.Although the methods are described in the context of the WTRU receivingthe HS-SCCH, the methods may also apply to other channels or othertechnologies.

In one example, the WTRU may be configured to receive the HS-SCCH usinga pre-coded pilot. As a result, the amount of pilot power used by thenetwork may be dynamically adapted and optimized. In a conventionalsystem, the HS-SCCH may be demodulated using the common pilot and theWTRU is aware of the spreading code and pilot sequence to use fordemodulation. With pre-coded pilots, a new set of pilot resources mayneed to be used for demodulation purposes. Methods for use in the WTRUto determine which pilot resource (i.e., channelization code, pilotsequence) to use are described herein.

In a first set of methods, the WTRU is configured with a specific pilotresource, or set of resources for decoding the HS-SCCH and, optionally,the associated HS-PDSCH. In one example, the WTRU may receive theconfiguration via RRC signaling. Then, the WTRU may attempt todemodulate and decode the HS-SCCH using the configured pilot resource.

From a resource allocation perspective, the RNC may allocate a differentpilot resource to every WTRU. However, this approach may consume a largenumber of channelization codes and may be inefficient as only a fractionof WTRUs are expected to receive HS-DSCH transmission on any given TTI.

In order to improve the efficiency of the pilot resource allocation, itmay be advantageous to allocate the same pilot resource or set of pilotresources to more than one WTRU. Each pilot resource may only be usedfor a single WTRU at a time. The WTRU may use each pilot resource forchannel estimation of a different layer. The pilot resource-layerassociation may be configurable or implicit, for example, based on fixedrules known by both the WTRU and Node B.

In order to allow as many WTRUs as possible to be scheduled with anHS-SCCH, the same set of pilot resources may be allocated to more thanone WTRU with a potentially different pilot to layer association foreach WTRU. This may provide the Node B with the additional flexibilityto potentially schedule more than one WTRU, for example, MU-MIMOoperation, from the same pilot resource set in a single TTI providedthat the actual pilot resources used for each WTRU are not the samesimultaneously.

Table 7 is an example of potential pilot resource allocation to multipleWTRUs.

TABLE 7 Pilot Pilot resource associated layer resource UE₁ UE₂ UE₃ UE₄P0 L0, L3 L2 L1 HS-SCCH P1 L1 L0, L3 L2 HS-SCCH P2 L2 L1 L0, L3 HS-SCCHP3 L3 L2 L1 L0, HS-SCCHEach WTRU may be configured with a set of pilot resources (P0 to P3 inthis example) and each pilot resource may be associated with a specificlayer. In this example, the layers are L0, . . . , L3 and the HS-SCCH isfurther associated with L0. While each WTRU is configured with the sameset of pilot resources, each resource may be associated with a differentlayer.

The number of pilot resources and WTRUs may differ than what is shown inTable 7. For example, the pilot-resource to layer association may not bemutually exclusive.

To further improve the reliability of HS-SCCH reception, the HS-SCCH maybe placed on the layer that has the best signal quality. When a Node Bperforms association of pilot resource to the layers, the Node B may befurther required to apply the pilot resource associated to HS-SCCH tothe precoding weight that has the best CQI report or another type ofperformance measure. For example, in Table 7, WTRU₁ may assign P0 to itsbest layer and WTRU₄ may have P3 transmitted on its best layer.

In a second set of methods, the WTRU may be configured with a set ofHS-SCCH codes to monitor and there may be one or more associated pilotresources for each HS-SCCH code. The WTRU attempts to decode eachconfigured HS-SCCH code using the associated pilot for demodulation andchannel filtering.

Because the number of pilot resources to be reserved by the network forcontrol-channel demodulation purposes is of the same order as the numberof HS-SCCH codes, the pilot resource used for the associated HS-PDSCHmay be different than the pilot resource used for the HS-SCCH. As aresult, the Node B may transmit the HS-SCCH with a different precodingweight.

FIG. 18 is an example of pilot resource allocation for demodulation ofHS-SCCH and HS-PDSCH. FIG. 18 includes HS-SCCH 1801 and HS-PDSCH 1802.Each channel 1801 and 1802 includes pilot resources #0 and #1. Pilotresource #0 corresponds to P0 1804 and pilot resource #1 corresponds toP1 1803.

The pilot resource used for the associated HS-PDSCH may also be the sameas the pilot resource used for the HS-SCCH. Because the HS-SCCH andassociated HS-PDSCH overlap in time, the same pilot resource may not beused in adjacent TTIs. This may be achieved by allocating two sets ofpilot resources for each HS-SCCH code and using them in timealternation. Provided there is an appropriate configuration, this mayprevent pilot resource collision. The WTRU may be configured with twosets of pilot resources for each HS-SCCH, and the WTRU may use them intime-alternation for demodulating the HS-SCCH and the associatedHS-PDSCH, if present, according to a fixed rule. FIG. 18 shows that P0and P1 are the two pilot resources for a specific HS-SCCH code.

FIG. 19 is an example of pilot resource monitoring in the presence oftransmission. FIG. 19 includes HS-SCCH 1901 and HS-PDSCH 1902. Eachchannel 1901 and 1902 includes pilot resources #0 and #1. Pilot resource#0 corresponds to P0 1904 and pilot resource #1 corresponds to P1 1903.

Additional rules may be used to simplify the WTRU processing. Forexample, when the WTRU receives an actual HS-SCCH with associated dataon the HS-PDSCH, the WTRU may use the same pilot resource for channelestimation on subsequent consecutive HS-DSCH transmissions. This maysimplify the WTRU channel estimation procedure as it may not need totrack two different channel estimates (from different pilot resources)during subsequent transmission. Accordingly, when the WTRU decodes itsH-RNTI successfully on the HS-SCCH, the WTRU may use the same pilotresource for demodulating the HS-SCCH on the next TTI. If the next TTIdoes not carry a transmission for that WTRU, the WTRU may revert to thepredefined pilot resource schedule on the following TTI.

In another method, the WTRU may be configured with a set of pilotresources for HS-SCCH monitoring and may blindly demodulate the HS-SCCH.The WTRU may attempt to decode each configured HS-SCCH with each pilotresource configured until the WTRU detects its H-RNTI or until the WTRUhas exhausted the search.

In another method, the WTRU may be configured to monitor a broadcastchannel indicating the pilot resource to use for a particular HS-SCCHcode.

In a common pilot scenario, the WTRU may be configured to estimate thechannel based on a set of common pilot channels. This is similar toconventional MIMO operations from Release 7 where the Node B transmitspre-coded HS-PDSCH channels and indicates an index to the pre-codingweight to the WTRU. However, here, the HS-SCCH may also be pre-coded bythe Node B in order to improve the cell coverage.

Because it may be preferred from the demodulation performancepoint-of-view that the WTRU is aware of a priori, the actual weightsused for HS-SCCH pre-coding, indicating the weights on the HS-SCCHitself, may not be sufficient.

In a first method, the WTRU may be configured with a set of precodingweights that may be used for HS-SCCH precoding. In one example, the WTRUmay blindly determine the HS-SCCH pre-coding weights by attempting todecode the HS-SCCH with each precoding weight in the configured set.Optionally, the precoding weight indicated on the HS-SCCH for HS-PDSCHmay be the same as the HS-SCCH precoding weight. The WTRU may then makecorrection to its channel estimate if its precoding weight estimate forHS-SCCH is wrong in the first place.

In a second method, the WTRU may be configured with a set of precodingweights and one or more parameters describing a schedule for the HS-SCCHprecoding weights. In each HS-SCCH subframe, the WTRU may determine thescheduled HS-SCCH precoding weights based on the configured parametersand potentially the connection frame number (CFN). The WTRU may usethese weights to attempt decoding the HS-SCCH. Here, the WTRU may usedifferent precoding weights, for example, the ones indicated in thedecoded HS-SCCH, to demodulate the associated HS-PDSCH.

In a third method, the WTRU may also be configured with a set ofprecoding weights. The WTRU may determine the actual weights used for aparticular HS-SCCH subframe and HS-SCCH code based on a separate signalbroadcast from the Node B. This new signal carries the precoding weightindex for each configured HS-SCCH code.

In a fourth method, the HS-SCCH may be precoded according to theprecoding weight used in the last sub-frame of HS-PDSCH that wastransmitted to this WTRU. The WTRU may be required to store the usedprecoding weight in the memory and use it when decoding the HS-SCCH thatcomes next. Here, the WTRU may be allowed to use same or differentprecoding weights, for example, the ones indicated in the decodedHS-SCCH, to demodulate the associated HS-PDSCH. The HS-SCCH may beprecoded by using the same precoding weight carried for the associatedHS-PDSCH sub-frame at an initial sub-frame of a downlink transmission orif the WTRU has been idling for an excessive period of time. Here, thefirst sub-frame of HS-SCCH may be decoded by blind detection of theprecoding weight.

Methods for control information processing may include methods to signaldownlink control information for a maximum of 2 codewords or 4codewords.

For signaling downlink control information for a maximum of 2 codewords,a non-codebook-based MIMO transmission structure may not require theWTRU to know the precoder applied at the transmitter for datademodulation. On the other hand, the WTRU may need such knowledge todemodulate and decode for a codebook-based MIMO transmission. Signalingmethods for both codebook-based and non-codebook-based MIMOtransmissions are discussed below.

As previously described, no precoding information may need to besignaled to the WTRU. Therefore, the precoding weight information fieldxpwipb1, xpwipb2 of the existing HS-SCCH type 3 may be reused for otherpurposes. For example, combined with modulation scheme and number oftransport blocks information field xms1, xms2, xms3, the precodingweight information field may be used to signal rank information up torank 4.

Table 8 is a first example mapping of X_(pwi), X_(ms).

TABLE 8 Modulation Modulation for for xms, 1, primary secondary Numberof xpwipb, 1, xms, 2, transport transport transport xpwipb, 2 xms, 3block block blocks 00: rank 2 111 16QAM 16QAM 2 01: rank 3 10: rank 400: rank 2 110 16QAM QPSK 2 01: rank 3 10: rank 4 If xccs, 7 = 1, then101 64QAM Indicated by Indicated by 00: rank 2 xccs, 7 xccs, 7 01: rank3 10: rank 4 Otherwise, n/a n/a 100 16QAM n/a 1 00: rank 2 011 QPSK QPSK2 01: rank 3 10: rank 4 00: rank 2 010 64QAM 64QAM 2 01: rank 3 10: rank4 00: rank 2 001 64QAM 16QAM 2 01: rank 3 10: rank 4 n/a 000 QPSK n/a 1As one example, Table 8 shows how to use existing weight informationfield xpwipb and modulation scheme and number transport blocksinformation field xms to signal the rank information. The weightinformation field xpwipb may be used to signal rank information (rank 2,3, or 4) when the number of transport blocks is two. There may be nochange on part 2 of the existing HS-SCCH type 3 channel. The benefit ofthis example is that at the WTRU side there may be very few changes onthe decoding of HS-SCCH type 3 channel. The only change may be thereinterpretation of the xpwipb field when 4-branch DL MIMO isconfigured.

Since there are a total of 21 different combinations of modulationscheme and rank, 5 bit information may be sufficient to convey all ofthem. Table 9 is a second example mapping of X_(pwi), X_(ms).

TABLE 9 Modulation Modulation xms, 1, for primary for secondary Numberof xpwipb, 1, xms, 2, transport transport transport xpwipb, 2 xms, 3block block blocks rank 00 111 16QAM 16QAM 2 2 01 3 10 4 00 110 16QAMQPSK 2 2 01 3 10 4 00 101 64QAM QPSK 2 2 01 3 10 4 11 101 64QAM n/a 1 1n/a 100 16QAM n/a 1 1 00 011 QPSK QPSK 2 2 01 3 10 4 00 010 64QAM 64QAM2 2 01 3 10 4 00 001 64QAM 16QAM 2 2 01 3 10 4 n/a 000 QPSK n/a 1 1

As another example shown in Table 9, both xpwipb and xms fields may beused, 5-bit in total, to signal rank and modulation scheme andconsequently there may be no need to use X_(ccs,7) to signal modulationor rank information and the channelization code-set mapping may bedefined as follows.

Given P (multi-)codes starting at code O, the information-field may becalculated using the unsigned binary representation of integers for thefirst three bits (code group indicator) of which x_(ccs,1) is the MSBusing the following equation:

x _(ccs,1) , x _(ccs,2) , x _(ccs,3)=min(P−1,15−P),   Equation (12)

The information-field may be calculated using the unsigned binaryrepresentation of integers for the last four bits (code offsetindicator) of which x_(ccs,4) is the most significant bit (MSB) usingthe following equation:

x _(ccs,4) , x _(ccs,5) , x _(ccs,6) , x _(ccs,7) =|O−1−└P/8┘*15|.  Equation (13)

Compared with existing channelization code-set mapping algorithm, thismethod may not put any restrictions on the selection of P and O viaHS-SCCH number as in the existing method and thus may increase thescheduling flexibility.

In Release 7 downlink MIMO, each transport block is mapped to a singlelayer. With the support of up to 4 layers on the downlink, a singletransport block may be carried over two layers, alone or in combinationwith another transport block, for example, on one or two differentlayers.

Table 10 is a third example mapping of X_(pwi), X_(ms).

TABLE 10 Modulation Modulation for for xms, 1, primary secondary Numberof xpwipb, 1, xms, 2, transport transport transport xpwipb, 2 xms, 3block block blocks 00: rank 2 111 16QAM 16QAM 2 01: rank 3 10: rank 400: rank 2 110 16QAM QPSK 2 01: rank 3 10: rank 4 If xccs, 7 = 1, then101 64QAM Indicated by Indicated by 00: rank 2 xccs, 7 xccs, 7 01: rank3 10: rank 4 Otherwise, 00: rank 1 01: rank 2 00: rank 1 100 16QAM n/a 101: rank 2 00: rank 2 011 QPSK QPSK 2 01: rank 3 10: rank 4 00: rank 2010 64QAM 64QAM 2 01: rank 3 10: rank 4 00: rank 2 001 64QAM 16QAM 2 01:rank 3 10: rank 4 00: rank 1 000 QPSK n/a 1 01: rank 2Table 10 shows an example of alternate mapping derive from Table 8.

Table 11 is a fourth example mapping of X_(pwi), X_(ms).

TABLE 11 Modulation Modulation xms, 1, for primary for secondary Numberof xpwipb, 1, xms, 2, transport transport transport xpwipb, 2 xms, 3block block blocks rank 00 111 16QAM 16QAM 2 2 01 3 10 4 00 110 16QAMQPSK 2 2 01 3 10 4 00 101 64QAM QPSK 2 2 01 3 10 4 11 101 64QAM n/a 1 100 100 2 01 100 16QAM n/a 1 1 10 2 00 011 QPSK QPSK 2 2 01 3 10 4 00 01064QAM 64QAM 2 2 01 3 10 4 00 001 64QAM 16QAM 2 2 01 3 10 4 00 000 QPSKn/a 1 1 01 2Table 11 shows an example of alternate mapping derived from Table 9.

In another alternative, it may be assumed that transport blocks may onlybe carried with one or two layers, and when two transport blocks aretransmitted, the Node-B may use three or four layers. With suchrestriction, a single bit of X_(pwi) may be needed to signal the rankand the other bit may be reserved for future use. Table 12 is a fifthexample mapping of X_(pwi), X_(ms).

TABLE 12 Modulation Modulation for for xms, 1, primary secondary Numberof xms, 2, transport transport transport xpwipb, 1 xms, 3 block blockblocks 0: rank 3 111 16QAM 16QAM 2 1: rank 4 0: rank 3 110 16QAM QPSK 21: rank 4 If xccs, 7 = 1, then 101 64QAM Indicated by Indicated by 0:rank 3 xccs, 7 xccs, 7 1: rank 4 Otherwise, 0: rank 1 1: rank 2 0: rank1 100 16QAM n/a 1 1: rank 2 0: rank 3 011 QPSK QPSK 2 1: rank 4 0: rank3 010 64QAM 64QAM 2 1: rank 4 0: rank 3 001 64QAM 16QAM 2 1: rank 4 0:rank 3 000 QPSK n/a 1 1: rank 4

Table 13 is a sixth example mapping of X_(pwi), X_(ms).

TABLE 13 Modulation Modulation xms, 1, for primary for secondary Numberof xpwipb, 1, xms, 2, transport transport transport xpwipb, 2 xms, 3block block blocks rank 00 111 16QAM 16QAM 2 3 01 4 00 110 16QAM QPSK 23 01 4 00 101 64QAM QPSK 2 3 01 4 10 101 64QAM n/a 1 1 11 2 00 100 16QAMn/a 1 1 01 2 00 011 QPSK QPSK 2 3 01 4 00 010 64QAM 64QAM 2 3 01 4 00001 64QAM 16QAM 2 3 01 4 00 000 QPSK n/a 1 1 01 2

Table 13 shows another example of alternate mapping derived from Table12, whereas in Table 9 and 11, X_(ccs,7) is not used for indicating themodulation format. In this example, both bits of X_(pwi) may be needed.One of the bits may be used to differentiate the modulation scheme andnumber of transport blocks replacing the function of X_(ccs,7).

For codebook-based MIMO transmission scheme, not only may the rankinformation need to be signaled to the WTRU, but also the precodingweight information may need to be signaled. Additional bits may berequired in order to signal precoding weight information compared toRelease 7 MIMO. Therefore, the HS-SCCH type 3 may not be directly reusedor extended to support 4-branch DL MIMO and a new type of HS-SCCH may bedesigned. Without loss of generality, the new HS-SCCH channel may benamed HS-SCCH type 4. HS-SCCH type 4 may be used when the WTRU isconfigured in 4Tx MIMO mode.

For HS-SCCH type 4 content, if one transport block is transmitted on theassociated HS-PDSCH(s), the following information may be transmitted bymeans of the HS-SCCH type 4 physical channel.

Channelization-code-set information may be transmitted by means of theHS-SCCH type 4 physical channel using 7 bits, for example, x_(ccs,1),x_(ccs,2), . . . , x_(ccs,7).

Modulation scheme and number of transport blocks information may betransmitted by means of the HS-SCCH type 4 physical channel using 3bits, for example, x_(ms,1), x_(ms,2), x_(ms,3).

Rank information may be transmitted by means of the HS-SCCH type 4physical channel using 2 bits, for example, x_(ri,1), x_(ri,2). Thetransmission of rank information may be optional.

Precoding weight information may be transmitted by means of the HS-SCCHtype 4 physical channel using 4 bits, for example, x_(pwipb,1),x_(pwipb,2), x_(pwipb,3), x_(pwipb,4).

Transport-block size information may be transmitted by means of theHS-SCCH type 4 physical channel using 6 bits, for example, x_(tbspb,1),x_(tbspb,2), . . . , x_(tbspb,6).

Hybrid-ARQ process information may be transmitted by means of theHS-SCCH type 4 physical channel using 4 bits, for example, x_(hap,1),x_(hap,2), . . . , x_(hap,4).

Redundancy and constellation version may be transmitted by means of theHS-SCCH type 4 physical channel using 2 bits, for example, x_(rvpb,1),x_(rvpb,2).

WTRU identity information may be transmitted by means of the HS-SCCHtype 4 physical channel using 16 bits, for example, x_(wtru,1),x_(wtru,2), . . . , x_(wtru,16).

For HS-SCCH type 4 content, if two transport blocks are transmitted onthe associated HS-PDSCHs, the following information may transmitted bymeans of the HS-SCCH type 4 physical channel.

Channelization-code-set information may be transmitted by means of theHS-SCCH type 4 physical channel using 7 bits, for example, x_(ccs,1),x_(ccs,2), . . . , x_(ccs,7).

Modulation scheme and number of transport blocks information may betransmitted by means of the HS-SCCH type 4 physical channel using 3bits, for example, x_(ms,1), x_(ms,2), x_(ms,3).

Rank information may be transmitted by means of the HS-SCCH type 4physical channel using 2 bits, for example, x_(ri,1), x_(ri,2). Rankinformation may be optional.

Precoding weight information may be transmitted by means of the HS-SCCHtype 4 physical channel using 4 bits, for example, x_(pwipb,1),x_(pwipb,2), x_(pwipb,3), x_(pwipb,4).

Transport-block size information for the primary transport block may betransmitted by means of the HS-SCCH type 4 physical channel using 6bits, for example, x_(tbspb,1), x_(tbspb,2), . . . , x_(tbspb,6).

Transport-block size information for the secondary transport block maybe transmitted by means of the HS-SCCH type 4 physical channel using 6bits, for example, x_(tbssb,1), x_(tbssb,2), . . . , x_(tbssb,6).

Hybrid-ARQ process information may be transmitted by means of theHS-SCCH type 4 physical channel using 4 bits, for example, x_(hap,1),x_(hap,2), . . . , x_(hap,4).

Redundancy and constellation version for the primary transport block maybe transmitted by means of the HS-SCCH type 4 physical channel using 2bits, for example, x_(rvpb,1), x_(rvpb,2).

Redundancy and constellation version for the secondary transport blockmay be transmitted by means of the HS-SCCH type 4 physical channel using2 bits, for example, x_(rvsb,1), x_(rvsb,2).

WTRU identity information may be transmitted by means of the HS-SCCHtype 4 physical channel using 16 bits, for example, x_(wtru,1),x_(wtru,2), . . . , x_(wtru,16).

In an alternate embodiment of the content, the rank information may bederived implicitly from the precoding information; therefore the rankinformation becomes optional depending on the implementation. In suchcases, the precoding information may consist of an index to a precollingmatrix which is pre-configured with a fixed number of layers.

FIG. 20 is an example of the coding chain for HS-SCCH type 4. FIG. 20includes a first multiplexer 2005 and a second multiplexer 2010.Channelization code set information, modulation scheme and transportblock information, rank information, and precolling weight information2001 may be put into a first multiplexer 2005. The inclusion of rankinformation may be optional. The output of the first multiplexer 2005may then be channel coded using a first channel coding 2015. The outputof the first channel coding 2015 may then be rate matched using a firstrate matching 1 2020. The output of the first rate matching 2020 maythen be masked with WTRU-specific masking 2025. WTRU identityinformation may be included in the WTRU-specific masking 2025.

Transport-block size information for the primary transport block,transport-block size information for the secondary transport block,Hybrid-ARQ process information, redundancy and constellation version forthe primary transport block, and redundancy and constellation versionfor the secondary transport block 2002 may be input to a secondmultiplexer 2010. The output of the second multiplexer 2010 may receiveWTRU-specific CRC attachment 2030. WTRU identity information may beincluded the WTRU-specific CRC attachment 2030. The output may then bechannel coded using a second channel coding 2035. The output of thesecond channel coding 2035 may then be rate matched using a second ratematching 2040. The output of the second rate matching 2040 may then becombined with the WTRU-specific masking 2025 output for physical channelmapping 2045.

For signaling downlink control information for a maximum of 4 codewords,the Node-B may need to signal the transport block size and redundancyand constellation version for each codeword.

For a non-codebook-based MIMO scheme, there may be no need to signalprecoding weight information. If one transport block is transmitted onthe associated HS-PDSCH(s), the following information may be transmittedby means of the HS-SCCH physical channel.

Channelization-code-set information may be transmitted by means of theHS-SCCH physical channel using 7 bits, for example, x_(ccs,1),x_(ccs,2), . . . , x_(ccs,7).

Modulation scheme and number of transport blocks information may betransmitted by means of the HS-SCCH physical channel using 3 bits, forexample, x_(ms,1), x_(ms,2), x_(ms,3).

Rank information may be transmitted by means of the HS-SCCH physicalchannel using 2 bits, for example, x_(ri,1), x_(ri,2).

Transport-block size information may be transmitted by means of theHS-SCCH physical channel using 6 bits, for example, x_(tbspb,1),x_(tbspb,2), . . . , x_(tbspb,6).

Hybrid-ARQ process information may be transmitted by means of theHS-SCCH physical channel using 4 bits, for example, x_(hap,1),x_(hap,2), . . . , x_(hap,4).

Redundancy and constellation version may be transmitted by means of theHS-SCCH physical channel using 2 bits, for example, x_(rvpb,1),x_(rvpb,2).

WTRU identity information may be transmitted by means of the HS-SCCHphysical channel using 16 bits, for example, x_(wtru,1), x_(wtru,2), . .. , x_(wtru,16).

If two transport blocks are transmitted on the associated HS-PDSCHs, thefollowing information may be transmitted by means of the HS-SCCHphysical channel.

Channelization-code-set information may be transmitted by means of theHS-SCCH physical channel using 7 bits, for example, x_(ccs,1),x_(ccs,2), . . . , x_(ccs,7).

Modulation scheme and number of transport blocks information may betransmitted by means of the HS-SCCH physical channel using 3 bits, forexample, x_(ms,1), x_(ms,2), x_(ms,3).

Rank information may be transmitted by means of the HS-SCCH physicalchannel using 2 bits, for example, x_(ri,1), x_(ri,2).

Transport-block size information for the primary transport block may betransmitted by means of the HS-SCCH physical channel using 6 bits, forexample, x_(tbspb,1), x_(tbspb,2), . . . , x_(tbspb,6).

Transport-block size information for the secondary transport block maybe transmitted by means of the HS-SCCH physical channel using 6 bits,for example, x_(tbssb,1), x_(tbssb,2), . . . , x_(tbssb,6).

Hybrid-ARQ process information may be transmitted by means of theHS-SCCH physical channel using 4 bits, for example, x_(hap,1),x_(hap,2), . . . , x_(hap,4).

Redundancy and constellation version for the primary transport block maybe transmitted by means of the HS-SCCH physical channel using 2 bits,for example, x_(rvpb,1), x_(rvpb,2).

Redundancy and constellation version for the secondary transport blockmay be transmitted by means of the HS-SCCH physical channel using 2bits, x_(rvsb,1), x_(rvsb,2).

WTRU identity information may be transmitted by means of the HS-SCCHphysical channel using 16 bits, for example, x_(wtru,1), x_(wtru,2), . .. , x_(wtru,16).

If three transport blocks are transmitted on the associated HS-PDSCHs,the following information may be transmitted by means of the HS-SCCHphysical channel.

Channelization-code-set information may be transmitted by means of theHS-SCCH physical channel using 7 bits, for example, x_(ccs,1),x_(ccs,2), . . . , x_(ccs,7).

Modulation scheme and number of transport blocks information may betransmitted by means of the HS-SCCH physical channel using 3 bits, forexample, x_(ms,1), x_(ms,2), x_(ms,3).

Rank information may be transmitted by means of the HS-SCCH physicalchannel using 2 bits, for example, x_(ri,1), x_(ri,2).

Transport-block size information for the primary transport block may betransmitted by means of the HS-SCCH physical channel using 6 bits, forexample, x_(tbspb,1), x_(tbspb,2), . . . , x_(tbspb,6).

Transport-block size information for the secondary transport block maybe transmitted by means of the HS-SCCH physical channel using 6 bits,for example, x_(tbssb,1), x_(tbssb,2), . . . , x_(tbssb,6).

Transport-block size information for the third transport block may betransmitted by means of the HS-SCCH physical channel using 6 bits, forexample, x_(tbs3,1), x_(tbs3,2), . . . , x_(tbs3,6).

Hybrid-ARQ process information may be transmitted by means of theHS-SCCH physical channel using 4 bits, for example, x_(hap,1),x_(hap,2), . . . , x_(hap,4).

Redundancy and constellation version for the primary transport block maybe transmitted by means of the HS-SCCH physical channel using 2 bits,for example, x_(rvpb,1), x_(rvpb,2).

Redundancy and constellation version for the secondary transport blockmay be transmitted by means of the HS-SCCH physical channel using 2bits, for example, x_(rvsb,1), x_(rvsb,2).

Redundancy and constellation version for the third transport block maybe transmitted by means of the HS-SCCH physical channel using 2 bits,for example, x_(rv3,1), x_(rv3,2).

WTRU identity information may be transmitted by means of the HS-SCCHphysical channel using 16 bits, for example, x_(wtru,1), x_(wtru,2), . .. , x_(wtru,16).

If four transport blocks are transmitted on the associated HS-PDSCHs,the following information is transmitted by means of the HS-SCCHphysical channel:

Channelization-code-set information may be transmitted by means of theHS-SCCH physical channel using 7 bits, for example, x_(ccs,1),x_(ccs,2), . . . , x_(ccs,7).

Modulation scheme and number of transport blocks information may betransmitted by means of the HS-SCCH physical channel using 3 bits, forexample, x_(ms,1), x_(ms,2), x_(ms,3).

Rank information may be transmitted by means of the HS-SCCH physicalchannel using 2 bits, for example, x_(ri,1), x_(ri,2).

Transport-block size information for the primary transport block may betransmitted by means of the HS-SCCH physical channel using 6 bits, forexample, x_(tbspb,1), x_(tbspb,2), . . . , x_(tbspb,6).

Transport-block size information for the secondary transport block maybe transmitted by means of the HS-SCCH physical channel using 6 bits,for example, x_(tbssb,1), x_(tbssb,2), . . . , x_(tbssb,6).

Transport-block size information for the third transport block may betransmitted by means of the HS-SCCH physical channel using 6 bits, forexample, x_(tbs3,1), x_(tbs3,2), . . . , x_(tbs3,6).

Hybrid-ARQ process information may be transmitted by means of theHS-SCCH physical channel using 4 bits, for example, x_(hap,1),x_(hap,2), . . . , x_(hap,4).

Redundancy and constellation version for the primary transport block maybe transmitted by means of the HS-SCCH physical channel using 2 bits,for example, x_(rvpb,1), x_(rvpb,2).

Redundancy and constellation version for the secondary transport blockmay be transmitted by means of the HS-SCCH physical channel using 2bits, for example, x_(rvsb,1), x_(rvsb,2).

Redundancy and constellation version for the third transport block maybe transmitted by means of the HS-SCCH physical channel using 2 bits,for example, x_(rv3,1), x_(rv3,2).

Redundancy and constellation version for the fourth transport block maybe transmitted by means of the HS-SCCH physical channel using 2 bits,for example, x_(rv4,1), x_(rv4,2).

WTRU identity information may be transmitted by means of the HS-SCCHphysical channel using 16 bits, for example, x_(wtru,1), x_(wtru,2), . .. , x_(wtru,16).

Table 14 is an example mapping of bits X_(ri), X_(ms).

TABLE 14 Mod- Mod- Mod- Mod- ulation ulation ulation ulation for for forfor Number xms,1, primary secondary third fourth of xms,2, xri,1,transport transport transport transport transport xms,3  xri,2  blockblock block block blocks 111 11 64QAM 64QAM 64QAM 64QAM 4 110 11 64QAM64QAM 64QAM 16QAM 4 101 11 64QAM 64QAM 64QAM QPSK 4 100 11 64QAM 64QAM16QAM 16QAM 4 011 11 64QAM 64QAM 16QAM QPSK 4 001 11 64QAM 64QAM QPSKQPSK 4 000 11 64QAM 16QAM 16QAM 16QAM 4 010 11 64QAM 16QAM 16QAM QPSK 4010 10 64QAM 16QAM QPSK QPSK 4 101 10 64QAM QPSK QPSK QPSK 4 111 1016QAM 16QAM 16QAM 16QAM 4 110 10 16QAM 16QAM 16QAM QPSK 4 011 10 16QAM16QAM QPSK QPSK 4 001 10 16QAM QPSK QPSK QPSK 4 100 10 QPSK QPSK QPSKQPSK 4 000 10 64QAM 64QAM 64QAM n/a 3 010 01 64QAM 64QAM 16QAM n/a 3 101, 01 64QAM 64QAM QPSK n/a 3 xccs, 7 = 1 101, 01 64QAM 16QAM 16QAMn/a 3 xccs, 7 = 0 111 01 64QAM 16QAM QPSK n/a 3 110 01 64QAM QPSK QPSKn/a 3 011 01 16QAM 16QAM 16QAM n/a 3 001 01 16QAM 16QAM QPSK n/a 3 10001 16QAM QPSK QPSK n/a 3 000 01 QPSK QPSK QPSK n/a 3 010 00 64QAM 64QAMn/a n/a 2 001 00 64QAM 16QAM n/a n/a 2  101, 00 64QAM QPSK n/a n/a 2xccs, 7 = 0 111 00 16QAM 16QAM n/a n/a 2 110 00 16QAM QPSK n/a n/a 2 01100 QPSK QPSK n/a n/a 2  101, 00 64QAM n/a n/a n/a 1 xccs, 7 = 1 100 0016QAM n/a n/a n/a 1 000 00 QPSK n/a n/a n/a 1

As there are 34 different combinations of modulation type and number oftransport blocks illustrated in Table 14, the coding of 9 differentcombinations of modulation type and number of transport blocks definedin Release 7 MIMO may be used as the base line. The introduction of 2additional bits xri,1 and xri,2, may provide a total of 36 differentcombinations to signal the modulation type and number of transportblocks for 4-Tx MIMO. One example of using xms and xri to indicate WTRUssuch control information is shown in Table 14. For rank 4 transmission,there may be no need to use x_(ccs,7) to indicate the modulation type.

FIG. 21 is an example of a coding chain for HS-SCCH for a non-codebookbased MIMO scheme with 4 transport blocks. FIG. 21 includes a firstmultiplexer 2105 and a second multiplexer 2110. Channelization code setinformation, modulation scheme and transport block information, and rankinformation 2101 may be put into a first multiplexer 2105. The output ofthe first multiplexer 2105 may then be channel coded using a firstchannel coding 2115. The output of the first channel coding 2115 maythen be rate matched using a first rate matching 2120. The output of thefirst rate matching 2120 may then be masked with WTRU-specific masking2125. WTRU identity information may be included in the WTRU-specificmasking 2125.

Transport-block size information for the primary transport block,transport-block size information for the secondary transport block,transport-block size information for the third transport block,transport-block size information for the fourth transport block,Hybrid-ARQ process information, redundancy and constellation version forthe primary transport block, redundancy and constellation version forthe secondary transport block, redundancy and constellation version forthe third transport block, and redundancy and constellation version forthe fourth transport block 2102 may be put into a second multiplexer2110. The output of the second multiplexer 2110 may receiveWTRU-specific CRC attachment 2130. WTRU identity information may beincluded the WTRU-specific CRC attachment 2130. The output may then bechannel coded using a second channel coding 2135. The output of thesecond channel coding 2135 may then be rate matched using a second ratematching 2140. The output of the second rate matching 2140 may then becombined with the WTRU-specific masking 2125 output for physical channelmapping 2145.

The indication of modulation type and number of transport blocks may usethe method described in a non-codebook-based scheme, as shown in Table14. However, the precoding weight information may need to be signaled inthis case as well.

If one transport block is transmitted on the associated HS-PDSCH(s) istransmitted, the following information may be transmitted by means ofthe HS-SCCH physical channel:

Channelization-code-set information may be transmitted by means of theHS-SCCH physical channel using 7 bits, for example, x_(ccs,1),x_(ccs,2), . . . , x_(ccs,7).

Modulation scheme and number of transport blocks information may betransmitted by means of the HS-SCCH physical channel using 3 bits, forexample, x_(ms,1), x_(ms,2), x_(ms,3).

Rank information may be transmitted by means of the HS-SCCH physicalchannel using 2 bits, for example, x_(ri,1), x_(ri,2). The transmissionof the rank information may be optional.

Precoding weight information may be transmitted by means of the HS-SCCHphysical channel using 4 bits, for example, x_(pwipb,1), x_(pwipb,2),x_(pwipb,3), x_(pwipb,4).

Transport-block size information, may be transmitted by means of theHS-SCCH physical channel using 6 bits, for example, x_(tbspb,1),x_(tbspb,2), . . . , x_(tbspb,6).

Hybrid-ARQ process information may be transmitted by means of theHS-SCCH physical channel using 4 bits, for example, x_(hap,1),x_(hap,2), . . . , x_(hap,4).

Redundancy and constellation version may be transmitted by means of theHS-SCCH physical channel using 2 bits, for example, x_(rvpb,1),x_(rvpb).

WTRU identity information may be transmitted by means of the HS-SCCHphysical channel using 16 bits, for example, x_(wtru,1), x_(wtru,2), . .. , x_(wtru,16).

If two transport blocks are transmitted on the associated HS-PDSCHs, thefollowing information may be transmitted by means of the HS-SCCHphysical channel:

Channelization-code-set information may be transmitted by means of theHS-SCCH physical channel using 7 bits, for example, x_(ccs,1),x_(ccs,2), . . . , x_(ccs,7).

Modulation scheme and number of transport blocks information may betransmitted by means of the HS-SCCH physical channel using 3 bits, forexample, x_(ms,1), x_(ms,2), x_(ms,3).

Rank information may be transmitted by means of the HS-SCCH physicalchannel using 2 bits, for example, x_(ri,1), x_(ri,2). The transmissionof the rank information may be optional.

Precoding weight information may be transmitted by means of the HS-SCCHphysical channel using 4 bits, for example, x_(pwipb,1), x_(pwipb,2),x_(pwipb,3), x_(pwipb,4).

Transport-block size information, may be transmitted by means of theHS-SCCH physical channel using 6 bits, for example, x_(tbspb,1),x_(tbspb,2), . . . , x_(tbspb,6).

Hybrid-ARQ process information may be transmitted by means of theHS-SCCH physical channel using 4 bits, for example, x_(hap,1),x_(hap,2), . . . , x_(hap,4).

Redundancy and constellation version may be transmitted by means of theHS-SCCH physical channel using 2 bits, for example, x_(rvpb,1),x_(rvpb).

Redundancy and constellation version for the secondary transport blockmay be transmitted by means of the HS-SCCH physical channel using 2bits, for example, x_(rvsb,1), x_(rvsb,2).

WTRU identity information may be transmitted by means of the HS-SCCHphysical channel using 16 bits, for example, x_(wtru,1), x_(wtru,2), . .. , x_(wtru,16).

If three transport blocks are transmitted on the associated HS-PDSCHs,the following information may be transmitted by means of the HS-SCCHphysical channel:

Channelization-code-set information may be transmitted by means of theHS-SCCH physical channel using 7 bits, for example, x_(ccs,1),x_(ccs,2), . . . , x_(ccs,7).

Modulation scheme and number of transport blocks information may betransmitted by means of the HS-SCCH physical channel using 3 bits, forexample, x_(ms,1), x_(ms,2), x_(ms,3).

Rank information may be transmitted by means of the HS-SCCH physicalchannel using 2 bits, for example, x_(ri,1), x_(ri,2). The transmissionof the rank information may be optional.

Precoding weight information may be transmitted by means of the HS-SCCHphysical channel using 4 bits, for example, x_(pwipb,1), x_(pwipb,2),x_(pwipb,3), x_(pwipb,4).

Transport-block size information, may be transmitted by means of theHS-SCCH physical channel using 6 bits, for example, x_(tbspb,1),x_(tbspb,2), . . . , x_(tbspb,6).

Hybrid-ARQ process information may be transmitted by means of theHS-SCCH physical channel using 4 bits, for example, x_(hap,1),x_(hap,2), . . . , x_(hap,4).

Redundancy and constellation version may be transmitted by means of theHS-SCCH physical channel using 2 bits, for example, x_(rvpb,1),x_(rvpb).

Redundancy and constellation version for the secondary transport blockmay be transmitted by means of the HS-SCCH physical channel using 2bits, for example, x_(rvsb,1), x_(rvsb,2).

Redundancy and constellation version for the third transport block maybe transmitted by means of the HS-SCCH physical channel using 2 bits,for example, x_(rv3,1), x_(rv3,2).

WTRU identity information may be transmitted by means of the HS-SCCHphysical channel using 16 bits, for example, x_(wtru,1), x_(wtru,2), . .. , x_(wtru,16).

If four transport blocks are transmitted on the associated HS-PDSCHs,the following information may be transmitted by means of the HS-SCCHphysical channel:

Channelization-code-set information may be transmitted by means of theHS-SCCH physical channel using 7 bits, for example, x_(ccs,1),x_(ccs,2), . . . , x_(ccs,7).

Modulation scheme and number of transport blocks information may betransmitted by means of the HS-SCCH physical channel using 3 bits, forexample, x_(ms,1), x_(ms,2), x_(ms,3).

Rank information may be transmitted by means of the HS-SCCH physicalchannel using 2 bits, for example, x_(ri,1), x_(ri,2). The transmissionof the rank information may be optional.

Precoding weight information may be transmitted by means of the HS-SCCHphysical channel using 4 bits, for example, x_(pwipb,1), x_(pwipb,2),x_(pwipb,3), x_(pwipb,4).

Transport-block size information, may be transmitted by means of theHS-SCCH physical channel using 6 bits, for example, x_(tbspb,1),x_(tbspb,2), . . . , x_(tbspb,6).

Hybrid-ARQ process information may be transmitted by means of theHS-SCCH physical channel using 4 bits, for example, x_(hap,1),x_(hap,2), . . . , x_(hap,4).

Redundancy and constellation version may be transmitted by means of theHS-SCCH physical channel using 2 bits, for example, x_(rvpb,1),x_(rvpb).

Redundancy and constellation version for the secondary transport blockmay be transmitted by means of the HS-SCCH physical channel using 2bits, for example, x_(rvsb,1), x_(rvsb,2).

Redundancy and constellation version for the third transport block maybe transmitted by means of the HS-SCCH physical channel using 2 bits,for example, x_(rv3,1), x_(rv3,2).

Redundancy and constellation version for the fourth transport block maybe transmitted by means of the HS-SCCH physical channel using 2 bits,for example, x_(rv4,1), x_(rv4,2).

WTRU identity information may be transmitted by means of the HS-SCCHphysical channel using 16 bits, for example, x_(wtru,1), x_(wtru,2), . .. , x_(wtru,16).

FIG. 22 is an example of a coding chain for HS-SCCH for a codebook basedMIMO scheme with 4 transport blocks. FIG. 22 includes a firstmultiplexer 2205 and a second multiplexer 2210. Channelization code setinformation, modulation scheme and transport block information, rankinformation, and precoding weight information 2201 may be put into afirst multiplexer 2205. The output of the first multiplexer 2205 maythen be channel coded using a first channel coding 2215. The output ofthe first channel coding 2215 may then be rate matched using a firstrate matching 2220. The output of the first rate matching 2220 may thenbe masked with WTRU-specific masking 2225. WTRU identity information maybe included in the WTRU-specific masking 2225.

Transport-block size information for the primary transport block,transport-block size information for the secondary transport block,transport-block size information for the third transport block,transport-block size information for the fourth transport block,Hybrid-ARQ process information, redundancy and constellation version forthe primary transport block, redundancy and constellation version forthe secondary transport block, redundancy and constellation version forthe third transport block, and redundancy and constellation version forthe fourth transport block 2202 may be put into a second multiplexer2210. The output of the second multiplexer 2210 may receiveWTRU-specific CRC attachment 2230. WTRU identity information may beincluded the WTRU-specific CRC attachment 2230. The output may then bechannel coded using a second channel coding 2235. The output of thesecond channel coding 2235 may then be rate matched using a second ratematching 2240. The output of the second rate matching 2240 may then becombined with the WTRU-specific masking 2225 output for physical channelmapping 2245.

The rank indication may also be carried out implicitly based on theprecoding weight information. Therefore the rank indication field may beoptional. The size of the fields is given as an example and the conceptsput forth herein may also be extended to different number of bits foreach field where applicable.

FIG. 23 is an example of a method for determining pilot information foreach data stream. FIG. 23 illustrates that a WTRU may receive aplurality of HS-SCCH resources including RRC configuration informationfor HSDPA, wherein the RRC configuration information includes dedicatedpilot information associated with each received HS-SCCH resource 2305.The WTRU may detect an H-RNTI associated with the WTRU in one of theplurality of HS-SCCH resources 2310. The WTRU may then determine pilotinformation, based on the dedicated pilot information and the one of theplurality of HS-SCCH resources, for a high speed physically downlinkshared channel (HS-PDSCH) associated with the one of the plurality ofHS-SCCH resources 2315. The dedicated pilot information may be either achannelization code or a base pilot resource index.

With availability of various types of pilot channel defined, the WTRUmay perform different measures to assist the network schedulers inmaking decision for the best transmission mode, or for the besttransmission point to receiver data. These measurements may includecombined CQIs from all transmission points. The measurements may bemeasured by the aid of the pilot channel commonly transmitted from allthe involved transmission points, an individual CQI for eachtransmission point by exploring the cell-specific pilot channels,optimal cross-cell precoding weights, if any of the cross-site precodingschemes are configured, and rank indication information if multiflowaggregation or MU-MIMO transmission modes are to be configured. Althoughthe WTRU may take any one or a combination of the above measurementssimultaneously by monitoring the pilot channels, reporting themeasurements to the network may result in overhead on the uplinkfeedback. Methods for reducing the overhead during WTRU reporting mayinclude any one or combination of the methods described below.

In a first embodiment, the WTRU compares the individual CQIs from eachtransmission point and feedback via layer 1 (L1) and determine the CQIthat indicates which one cell the WTRU is associated with.

In a second embodiment, the WTRU reports all of the measured CQIs via L1signaling. The WTRU may report one type of CQI (e.g. the combined CQI)in full precision and the other types of CQI in a differential mannerwith less precision.

In a third embodiment, the WTRU reports the CQI needed for atransmission mode using L1 signaling. The WTRU may transmit othermeasurements via a higher layer at a much slower update rate.

In a forth embodiment, the WTRU reports signal quality at higher layerand semi-dynamically reconfigures which transmission point to use. TheWTRU may report only the CQIs for that transmission point using L1signaling, at each configuration.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

What is claimed:
 1. A wireless transmit/receive unit (WTRU) comprising:a receiver; and a processor; and the receiver and the processor areconfigured to receive a radio resource control (RRC) message providingconfiguration information for at least one physical control channel, theconfiguration information including an indication of a pilot sequence ofthe physical control channel; and the receiver and the processor areconfigured to monitor the at least one physical control channel using apilot signal of the at least one physical control channel, wherein thepilot signal is derived from the pilot sequence.
 2. The WTRU of claim 1wherein the at least one control channel is received as a pre-codedsignal and the pilot bits have a same pre-coding as the at least onephysical control channel.
 3. The WTRU of claim 1 wherein the at leastone control channel is received on a plurality of layers, wherein eachof the plurality of layers has different pilot signals.
 4. The WTRU ofclaim 1 wherein the RRC message includes configuration information forat least one different physical control channel, the configurationinformation including a second indication of a second pilot sequence andthe receiver and the processor are further configured to monitor the atleast one different physical control channel using a second pilotsignal, wherein the second pilot signal is derived from the second pilotsequence.
 5. The WTRU of claim 1 wherein the receiver and the processormonitor the at least one physical control channel for a control messagehaving bits derived from a radio network terminal identifier (RNTI) ofthe WTRU, wherein the control message includes an indication ofresources for a physical shared channel and the receiver and theprocessor are further configured to receive the physical shared channelin the indicated resources.
 6. A method for use in a wirelesstransmit/receive unit (WTRU) comprising: receiving a radio resourcecontrol (RRC) message providing configuration information for at leastone physical control channel, the configuration information including anindication of a pilot sequence of the physical control channel; andmonitoring the at least one physical control channel using a pilotsignal of the at least one physical control channel, wherein the pilotsignal is derived from the pilot sequence.
 7. The method of claim 6wherein the at least one control channel is received as a pre-codedsignal and the pilot bits have a same pre-coding as the at least onephysical control channel.
 8. The method of claim 6 wherein the at leastone control channel is received on a plurality of layers, wherein eachof the plurality of layers has different pilot signals.
 9. The method ofclaim 6 wherein the RRC message includes configuration information forat least one different physical control channel, the configurationinformation including a second indication of a second pilot sequence andthe receiver and the processor are further configured to monitor the atleast one different physical control channel using a second pilotsignal, wherein the second pilot signal is derived from the second pilotsequence.
 10. The method of claim 6 wherein the receiver and theprocessor monitor the at least one physical control channel for acontrol message having bits derived from a radio network terminalidentifier (RNTI) of the WTRU, wherein the control message includes anindication of resources for a physical shared channel and the receiverand the processor are further configured to receive the physical sharedchannel in the indicated resources.